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An embedded shock-fitting technique on unstructured dynamic grids Comput. Fluids (IF 2.399) Pub Date : 2021-01-18 Dongyang Zou; Aldo Bonfiglioli; Renato Paciorri; Jun Liu
In this paper, a new shock-fitting technique based on unstructured dynamic grids is proposed to improve the performances of the unstructured “boundary” shock-fitting technique developed by Liu and co-workers in [1, 2]. The main feature of this new technique, which we call the “embedded” shock-fitting technique, is its capability to insert or remove shocks or parts thereof during the calculation. This
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The effect of initial amplitude and convergence ratio on instability development and deposited fluctuating kinetic energy in the single-mode Richtmyer-Meshkov instability in spherical implosions Comput. Fluids (IF 2.399) Pub Date : 2021-01-12 L. Heidt; M. Flaig; B. Thornber
This paper investigates the growth of perturbations on the inner surface of a dense imploding spherical shell due to hydrodynamic instabilities. The perturbations change in amplitude due to Richtmyer-Meshkov instability and Rayleigh-Taylor instability, geometric convergence, and compressibility. Two mode numbers (ℓ=5,50) and three different perturbation amplitudes (a0=0.1λ,0.01λ,0.001λ) are applied
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Droplet impact on nano-textured bumps: Topology effects Comput. Fluids (IF 2.399) Pub Date : 2021-01-12 Shakeel Ahmad; Jiyun Zhao; Aamer Shahzad; Muhammad Nafees Mumtaz Qadri; Hui Tang
Using the lattice Boltzmann method (LBM), the dynamics of a single droplet impacting on desert-beetle inspired, super-hydrophobic, nano-textured bumps was numerically investigated. The focus was placed on the effects of post height, inter-post spacing, bump radius of curvature and impact velocity represented by the Weber number. Three droplet states after the impact were captured, i.e., the suspended
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A dimensionless numerical mesh-free model for the compressible fluid flows Comput. Fluids (IF 2.399) Pub Date : 2021-01-12 Mohammed Rammane; Said Mesmoudi; Abdeljalil Tri; Bouazza Braikat; Noureddine Damil
In this paper, we propose a dimensionless numerical mesh-free model for the simulation of the compressible isothermal viscous flows. The novelty of this work consists to formulate the Navier-Stokes equations under a dimensionless form and to solve them by a high order mesh-free algorithm to simulate the compressible fluid flows. This algorithm combines a classical implicit Euler scheme, a high order
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The immersed boundary–lattice Boltzmann method for solving solid–fluid interaction problem with Navier–slip boundary condition Comput. Fluids (IF 2.399) Pub Date : 2021-01-12 Zhenyu Wang; Qiaolin He; Jizu Huang
To solve the solid–fluid interaction with Navier–slip boundary condition, we propose a new method in this paper. In this approach, the solid body is modeled by the Newton’s equations and the fluid is assumed to satisfy the discrete lattice Boltzmann equations. The Navier–slip boundary condition is applied as the velocity boundary condition for the solid–fluid interface. We discretize the Newton’s equations
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Commutative recursive filters for explicit-filter large-eddy simulation of turbulent flows Comput. Fluids (IF 2.399) Pub Date : 2021-01-09 Myeongkyun Kim; Jaeyong Jeong; Sanghyun Ha; Donghyun You
A recursive filtering technique is developed to improve the computational efficiency of explicit-filter large-eddy simulation in highly parallelized computational environments. In parallel computations on a partitioned domain, unlike in non-recursive explicit filtering in which a number of ghost cell layers for storing neighbor cell values to ensure communication with neighbor partitions is increased
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Eulerian-Eulerian simulation of dusty gas flows past a prism from subsonic to supersonic regimes using a modal discontinuous Galerkin method Comput. Fluids (IF 2.399) Pub Date : 2021-01-09 Omid Ejtehadi; R.S. Myong
The present work investigates the bubble formation and vortex shedding phenomena in the viscous flow of a compressible gas seeded with dust particles. A new modal discontinuous Galerkin method was developed for solving the two-fluid model of dusty gas flows. Most previous studies have been limited to flows with low Mach numbers without the presence of shock waves. This study considered a wider Mach
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Implementation of the transition model for high order discontinuous Galerkin method with hybrid discretization strategy Comput. Fluids (IF 2.399) Pub Date : 2021-01-08 Zhen-Hua Jiang; Chao Yan; Jian Yu
The γ-Reθt⌢transition model has been applied within the framework of high order discontinuous Galerkin (DG) discretization of Reynolds-averaged Navier-Stokes (RANS) equations. A hybrid discretization strategy that takes advantage of all available information from DG method is suggested for the implementation of the transition model. Some techniques for the spatial and temporal discretization are utilized
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A-posteriori LES assessment of subgrid-scale closures for bounded passive scalars Comput. Fluids (IF 2.399) Pub Date : 2021-01-08 L. Engelmann; M. Klein; A.M. Kempf
Scale similarity or gradient models represent attractive, functionally simple expressions for large eddy simulation (LES) subgridscale (SGS) models, showing excellent behaviour in a-priori LES studies for small to moderate filter sizes. However, when applied a-posteriori to real LES calculations, they frequently suffer from numerically unstable behavior. A recent regularization approach revealed promising
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Improvements in MLPG formulation for 3D wave interaction with fixed structures Comput. Fluids (IF 2.399) Pub Date : 2020-12-29 Shagun Agarwal; V. Sriram; Shiqiang Yan; K. Murali
This paper presents new developments in meshless local Petrov–Galerkin with Rankine source (MLPG_R) particle based method for studying interaction of waves with fixed structures in a numerical wave-tank. A new 3D formulation of the Lagrangian flow problem for incompressible fluid with optimised solution strategy is presented. The pressure Poisson equation is solved in local weak-form with integration
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State observer data assimilation for RANS with time-averaged 3D-PIV data Comput. Fluids (IF 2.399) Pub Date : 2020-12-29 Edoardo Saredi; Nikhilesh Tumuluru Ramesh; Andrea Sciacchitano; Fulvio Scarano
State observer techniques are investigated for the assimilation of three-dimensional velocity measurements into computational fluid dynamics simulations based on Reynolds-averaged Navier–Stokes (RANS) equations. The method relies on a forcing term, or observer, in the momentum equation, stemming from the difference between the computed velocity and the reference value, obtained by measurements or high-fidelity
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Thermal pseudo-potential lattice Boltzmann method for simulating cavitation bubbles collapse near a rigid boundary Comput. Fluids (IF 2.399) Pub Date : 2020-12-24 Haonan Peng; Jianmin Zhang; Xiaolong He; Yurong Wang
The thermodynamic problem of the cavitation bubble near a rigid boundary is always the key and difficult to capture in the cavitation phenomenon. In this paper, the double distribution function (DDF) thermal lattice Boltzmann method (LBM) is used to study the collapse process of a single and a dual cavitation bubble near a rigid boundary with a large density and viscosity ratio. The simulation results
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An Efficient Sliding Mesh Interface Method for High-Order Discontinuous Galerkin Schemes Comput. Fluids (IF 2.399) Pub Date : 2020-12-30 Jakob Dürrwächter; Marius Kurz; Patrick Kopper; Daniel Kempf; Claus-Dieter Munz; Andrea Beck
Sliding meshes are a powerful method to treat deformed domains in computational fluid dynamics, where different parts of the domain are in relative motion. In this paper, we present an efficient implementation of a sliding mesh method into a discontinuous Galerkin compressible Navier-Stokes solver and its application to a large eddy simulation of a 1-1/2 stage turbine. The method is based on the mortar
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Numerical simulation of non-reacting fuel-air coaxial jets by means of a novel high-order method Comput. Fluids (IF 2.399) Pub Date : 2020-12-21 N. Franchina; M. Savini; F. Bassi
The present work deals with the development of an original Discontinuous Galerkin (DG) finite element code and its application to compute the non-reactive aerodynamics of multicomponent gaseous mixtures in turbulent regime. Recent developments of the DG approach show great potential in computing high-order accurate solutions on arbitrarily complex grids even in the presence of strong discontinuities
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Lattice Boltzmann simulation of near/supercritical CO2 flow featuring a crossover formulation of the equation of state Comput. Fluids (IF 2.399) Pub Date : 2020-12-16 Bagdagul Kabdenova (Dauyeshova); Luis R. Rojas-Solórzano; Ernesto Monaco
In this work, we have incorporated a crossover equation of state into the pseudopotential multiphase Lattice Boltzmann Model (LBM) to improve the prediction of thermodynamic properties of fluids and their flow in near-critical and supercritical regions. Modeling carbon dioxide (CO2) properties in these regions is of increasing interest for industrial processes such as CO2 storage and heat transfer
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Reduced order modelling for a rotor-stator cavity using proper orthogonal decomposition Comput. Fluids (IF 2.399) Pub Date : 2020-12-16 Michel Onori; Nicholas J. Hills
The paper describes the Reduced Order Modelling (ROM) for the turbulent flow in a rotor-stator cavity, a configurations commonly encountered in secondary air system of aircraft engines. The proper orthogonal decomposition (POD) that uses data from Large Eddy Simulations (LES) is here considered in order to identify a set of orthonormal basis functions for the Galerkin projection of the Navier-Stokes
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Numerical study of longitudinal vein effects on the aerodynamic characteristics of a corrugated bio-airfoil Comput. Fluids (IF 2.399) Pub Date : 2020-12-16 Shidvash Vakilipour; Hadi Zarafshani; Jafar Al-Zaili
The purpose of the present study is to investigate the influence of cross-sectional veins topology on the flow pattern and aerodynamic performance of a pitching corrugated bio-inspired airfoil. To demonstrate the vein effects, a cross-section of Ashena Cyanea wing is modelled with three configurations. The airflow passing bio-airfoil is subjected to three Reynolds numbers of 1000, 5000, and 14000 and
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Numerical investigation of vortical flows over a close-coupled delta canard-wing configuration Comput. Fluids (IF 2.399) Pub Date : 2020-12-16 Kaan Yutuk; Alp Tikenogullari; Ismail H. Tuncer
In this study, vortex dominated flows over a close-coupled canard-wing-body configuration at high angles of attack are studied by using the open-source flow solver, SU2 in a parallel computing environment. Validation studies with solution adaptive grid refinements and turbulence models are first performed. The vortical flow fields due to the canard and wing vortices are assessed in terms of vortex
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On the comparison of LES data-driven reduced order approaches for hydroacoustic analysis Comput. Fluids (IF 2.399) Pub Date : 2020-12-16 Mahmoud Gadalla; Marta Cianferra; Marco Tezzele; Giovanni Stabile; Andrea Mola; Gianluigi Rozza
In this work, Dynamic Mode Decomposition (DMD) and Proper Orthogonal Decomposition (POD) methodologies are applied to hydroacoustic dataset computed using Large Eddy Simulation (LES) coupled with Ffowcs Williams and Hawkings (FWH) analogy. First, a low-dimensional description of the flow fields is presented with modal decomposition analysis. Sensitivity towards the DMD and POD bases truncation rank
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On the generation of turbulent inflow for hybrid RANS/LES jet flow simulations Comput. Fluids (IF 2.399) Pub Date : 2020-12-16 F. Gand; M. Huet
The present work is devoted to the assessment of a low-noise turbulence generation methodology used to produce boundary layer with three-dimensional resolved turbulence at the exit of a jet nozzle to reproduce experimental conditions. The method relies on the use of roughness elements introduced in the computational domain with Immersed Boundary Conditions and ZDES mode 3 (Wall Modelled LES branch
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The δ-ALE-SPH model: an arbitrary Lagrangian-Eulerian framework for the δ-SPH model with Particle Shifting Technique Comput. Fluids (IF 2.399) Pub Date : 2020-12-06 M. Antuono; P.N. Sun; S. Marrone; A. Colagrossi
The behaviour of a weakly-compressible SPH scheme obtained by rewriting the Navier-Stokes equations in an arbitrary Lagrangian-Eulerian (ALE) format is studied. Differently from previous works on ALE, which generally adopt conservative variables (i.e. mass and momentum) and rely on the use of Riemann solvers inside the spatial operators, the proposed model is expressed in terms of primitive variables
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Characterization of the turbulent wake of an axial-flow hydrokinetic turbine via large-eddy simulation Comput. Fluids (IF 2.399) Pub Date : 2020-12-16 Antonio Posa; Riccardo Broglia
Large-Eddy Simulation on a grid composed of about two billion points is utilized to characterize the turbulent wake of an axial-flow hydrokinetic turbine. The dominant role of the tip vortices is revealed, both in the near wake, where they are very coherent, and downstream, after development of instability. As long as the tip vortices are stable, sharp peaks of Reynolds stresses populate the outer
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Numerical modeling of an inductively coupled plasma torch using OpenFOAM Comput. Fluids (IF 2.399) Pub Date : 2020-12-08 Christian Busse; Ilya Tsivilskiy; Jörg Hildebrand; Jean Pierre Bergmann
A customized code using the free and fully open-source CFD software package OpenFOAM was developed to simulate a two-dimensional axisymmetric model of an inductively coupled plasma torch. To efficiently calculate the high-frequency magnetic fields generated by the inductive coil, a technique based on the vector potential formulation of Maxwell’s equations was implemented using the block coupled matrix
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An interface capturing method for liquid-gas flows at low-Mach number Comput. Fluids (IF 2.399) Pub Date : 2020-12-03 Federico Dalla Barba; Nicoló Scapin; Andreas D. Demou; Marco E. Rosti; Francesco Picano; Luca Brandt
Multiphase, compressible and viscous flows are of crucial importance in a wide range of scientific and engineering problems. Despite the large effort paid in the last decades to develop accurate and efficient numerical techniques to address this kind of problems, current models need to be further improved to address realistic applications. In this context, we propose a numerical approach to the simulation
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Numerical modeling for compressible two-phase flows and application to near-field underwater explosions Comput. Fluids (IF 2.399) Pub Date : 2020-12-07 Van-Tu Nguyen; Thanh-Hoang Phan; Trong-Nguyen Duy; Warn-Gyu Park
In this study, an accurate shock- and interface-capturing method using curvilinear body-fitted structured grids is introduced to simulate compressible multiphase flows with shockwaves. A five-equation model—proficient in capturing unsteady shocks in compressible multiphase flows without nonphysical spurious oscillations—was enhanced by extending it to a multidimensional general curvilinear coordinate
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Multi-material hydrodynamics with algebraic sharp interface capturing Comput. Fluids (IF 2.399) Pub Date : 2020-12-07 Aditya K. Pandare; Jacob Waltz; Jozsef Bakosi
A finite volume method for Eulerian multi-material hydrodynamics with sharp interface capturing is presented. The pressure-temperature non-equilibrium multi-material system with finite-rate pressure relaxation in mixed-cells is considered here. This pressure closure facilitates material-property-dependent pressure relaxation, rather than instantaneous pressure equilibration, which in turn allows the
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Direct numerical simulations of turbulent reacting flows with shock waves and stiff chemistry using many-core/GPU acceleration Comput. Fluids (IF 2.399) Pub Date : 2020-11-30 Swapnil Desai; Yu Jeong Kim; Wonsik Song; Minh Bau Luong; Francisco E. Hernández Pérez; Ramanan Sankaran; Hong G. Im
Compressible reacting flows may display sharp spatial variation related to shocks, contact discontinuities or reactive zones embedded within relatively smooth regions. The presence of such phenomena emphasizes the relevance of shock-capturing schemes such as the weighted essentially non-oscillatory (WENO) scheme as an essential ingredient of the numerical solver. However, these schemes are complex
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On a new algorithm for incorporating the contact angle forces in a simulation using the shallow water equation and smoothed particle hydrodynamics Comput. Fluids (IF 2.399) Pub Date : 2020-12-01 Simon Härdi; Michael Schreiner; Uwe Janoske
The simulation of a thin film on a small scale surface that covers only part of the domain must incorporate the contact angle force acting on the border between wetted and dry parts of the surface. A method to reconstruct this contact line and interpolate the resulting force while using smoothed particle hydrodynamics as discretization method is derived, using only geometrical properties to calculate
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Direct reconstruction method for discontinuous Galerkin methods on higher-order mixed-curved meshes III. Code optimization via tensor contraction Comput. Fluids (IF 2.399) Pub Date : 2020-12-03 Hojun You; Chongam Kim
The present study deals with the code optimization and its implementation of the direct reconstruction method (DRM) using the complete-search tensor contraction (CsTC) framework to extract the best performance of high-order methods on modern computing architectures. DRM was originally proposed to overcome severe computational costs of the physical domain-based discontinuous Galerkin (DG) method on
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Immersed boundary conditions for hypersonic flows using ENO-like least-square reconstruction Comput. Fluids (IF 2.399) Pub Date : 2020-11-25 Thibault Bridel-Bertomeu
In this study, we present an immersed boundary reconstruction method for the simulation of viscous compressible flows presenting strong discontinuities in the vicinity of the immersed body. The technique we propose is based on a weighted least-square reconstruction. Its major feature is that the weights are automatically adapted to the presence of a discontinuity within the least-square stencil by
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A parallel, object-oriented framework for unsteady free-wake analysis of multi-rotor/wing systems Comput. Fluids (IF 2.399) Pub Date : 2020-11-10 Cibin Joseph; Ranjith Mohan
The development, validation, and applications of an object-oriented free-wake solver for multi-rotor and fixed-wing systems are outlined here. Advantages of utilizing the object-oriented philosophy for modeling the multi-rotor/wing free-wake problem are described. To explore the feasibility of utilizing conventional desktop workstations, the vortex lattice methodology’s time complexity is examined
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A mass-momentum consistent, Volume-of-Fluid method for incompressible flow on staggered grids Comput. Fluids (IF 2.399) Pub Date : 2020-11-19 T. Arrufat; M. Crialesi-Esposito; D. Fuster; Y. Ling; L. Malan; S. Pal; R. Scardovelli; G. Tryggvason; S. Zaleski
The computation of flows with large density contrasts is notoriously difficult. To alleviate the difficulty we consider a discretization of the Navier-Stokes equation that advects mass and momentum in a consistent manner. Incompressible flow with capillary forces is modeled and the discretization is performed on a staggered grid of Marker and Cell type. The Volume-of-Fluid method is used to track the
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Single relaxation time entropic lattice Boltzmann methods: A developer’s perspective for stable and accurate simulations Comput. Fluids (IF 2.399) Pub Date : 2020-11-19 Anirudh Jonnalagadda; Atul Sharma; Amit Agrawal
There have been contradicting reports in the literature regarding the application of the Entropic LBM to various flow problems. In this paper, we aim to evaluate the various formulations of the Entropic LBM and elaborate on the construction and numerical implementation required for successfully running such simulations. Tests conducted on four different test cases over a large parameter range, along
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Application of half-way approach to discrete unified gas kinetic scheme for simulating pore-scale porous media flows Comput. Fluids (IF 2.399) Pub Date : 2020-10-30 Shi Tao; Liang Wang; Ya Ge; Qing He
Simulation of pore-scale porous media flows is generally considered to be a non-trivial task due to the complicacy of geometry structures involved. In the recent decades, the mesoscopic scheme of lattice Boltzmann equation (LBE), combined with the inherent half-way (HW) bounce-back boundary method has been proved to efficiently handle those complex flows. More recently, a new mesoscopic method called
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An isogeometric boundary element method for soft particles flowing in microfluidic channels Comput. Fluids (IF 2.399) Pub Date : 2020-11-10 J.M. Lyu; Paul G. Chen; G. Boedec; M. Leonetti; M. Jaeger
Understanding the flow of deformable particles such as liquid drops, synthetic capsules and vesicles, and biological cells confined in a small channel is essential to a wide range of potential chemical and biomedical engineering applications. Computer simulations of this kind of fluid-structure (membrane) interaction in low-Reynolds-number flows raise significant challenges faced by an intricate interplay
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Two approaches to calculating composition of rarefied gas mixture exposed to chemical reactions at flow through cylindrical channel Comput. Fluids (IF 2.399) Pub Date : 2020-10-24 M.Yu. Plotnikov; E.V. Shkarupa
Two approaches to calculating the change in the composition of a rarefied gas mixture due to gas-phase and heterogeneous reactions when it flows through a heated cylindrical channel into a vacuum are considered. The first approach is based on the direct simulation Monte Carlo (DSMC) method taking into account gas-phase reactions. The second one consists in combining the DSMC method without gas-phase
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DSMC simulation of two-step dissociation-recombination of hydrogen on tantalum surface Comput. Fluids (IF 2.399) Pub Date : 2020-10-29 Mikhail Plotnikov; Elena Shkarupa
The presented work is devoted to the development of new approaches to simulating heterogeneous reactions of hydrogen dissociation and recombination during its interaction with the solid surface within the framework of the direct simulation Monte Carlo (DSMC) method. The DSMC algorithm including a two-step model of hydrogen dissociation is developed. A new technique for simulating heterogeneous reactions
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Discontinuous Galerkin solution of the RANS and kL−k−log(ω) equations for natural and bypass transition Comput. Fluids (IF 2.399) Pub Date : 2020-10-14 M. Lorini; F. Bassi; A. Colombo; A. Ghidoni; G. Noventa
Transition modelling represents a key ingredient for improving the performance predictions of many industrial applications. Among transition models, local formulations seem to guarantee better robustness, accuracy and easiness of implementation in modern CFD solvers. These models have been proposed in the finite volume context to predict the laminar-turbulent transition, but only few attempts have
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A mesh adaptation strategy for complex wall-modeled turbomachinery LES Comput. Fluids (IF 2.399) Pub Date : 2020-10-14 Nicolas Odier; Adrien Thacker; Maël Harnieh; Gabriel Staffelbach; Laurent Gicquel; Florent Duchaine; Nicolás García Rosa; Jens-Dominik Müller
A mesh adaptation methodology for wall-modeled turbomachinery Large Eddy Simulation (LES) is proposed, simultaneously taking into account two quantities of interest: the average kinetic energy dissipation rate and the normalized wall distance y+. This strategy is first tested on a highly loaded transonic blade with separated flow, and is compared to wall-resolved LES results, as well as experimental
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Designing CFD methods for bandwidth—A physical approach Comput. Fluids (IF 2.399) Pub Date : 2020-10-22 Philip Roe
A hoped-for outcome from high-order CFD methods, in addition to achieving accurate solutions on fine grids, is to achieve useful answers on coarse grids. In this paper we note that this outcome is by no means automatic, and consider how the different quests of accuracy and bandwidth may be achieved. Although accuracy is exclusively a low-frequency property and so amenable to Taylor series analysis
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Multiple drops impact onto a liquid film: Direct numerical simulation and experimental validation Comput. Fluids (IF 2.399) Pub Date : 2020-10-13 S. Fest-Santini; J. Steigerwald; M. Santini; G.E. Cossali; B. Weigand
A simultaneous impact of three water drops (aligned with equidistant spacing) onto a solid wall covered by a thin liquid film is predicted by direct numerical simulation using the multiphase code Free Surface 3D (FS3D) which is based on the volume-of-fluid (VOF) method and uses the piecewise linear interface calculation (PLIC) method to reconstruct the interface. The numerically reproduced splashing
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Imposing mixed Dirichlet-Neumann-Robin boundary conditions on irregular domains in a level set/ghost fluid based finite difference framework Comput. Fluids (IF 2.399) Pub Date : 2020-10-18 Min Chai; Kun Luo; Haiou Wang; Shuihua Zheng; Jianren Fan
In this paper, an efficient, unified finite difference method for imposing mixed Dirichlet, Neumann and Robin boundary conditions on irregular domains is proposed, leveraging on our previous work [Chai et al., J. Comput. Phys. 400 (2020): 108890]. The level set method is applied to describe the arbitrarily-shaped interface, and the ghost fluid method is utilized to address the complex discontinuities
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Overnight industrial LES for external aerodynamics Comput. Fluids (IF 2.399) Pub Date : 2020-10-24 Rainald Löhner; Carsten Othmer; M. Mrosek; Alejandro Figueroa; Atis Degro
This paper summarizes the efforts carried out over the last year to achieve overnight industrial Large-Eddy Simulation (LES) runs for external car aerodynamics. The solver employed is based on adaptive cartesian blocks, uses explicit timestepping to advance the Navier-Stokes equations describing mildly compressible flows, and scales well to tens of thousands of cores. The capabilities developed to
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Multiresolution classification of turbulence features in image data through machine learning Comput. Fluids (IF 2.399) Pub Date : 2020-10-14 Jesus Pulido; Ricardo Dutra da Silva; Daniel Livescu; Bernd Hamann
During large-scale simulations, intermediate data products such as image databases have become popular due to their low relative storage cost and fast in-situ analysis. Serving as a form of data reduction, these image databases have become more acceptable to perform data analysis on. We present an image-space detection and classification system for extracting vortices at multiple scales through wavelet-based
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A turbulent eddy-viscosity surrogate modeling framework for Reynolds-Averaged Navier-Stokes simulations Comput. Fluids (IF 2.399) Pub Date : 2020-11-02 Romit Maulik; Himanshu Sharma; Saumil Patel; Bethany Lusch; Elise Jennings
The Reynolds-averaged Navier-Stokes (RANS) equations for steady-state assessment of incompressible turbulent flows remain the workhorse for practical computational fluid dynamics (CFD) applications. Consequently, improvements in speed or accuracy have the potential to affect a diverse range of applications. We introduce a machine learning framework for the surrogate modeling of steady-state turbulent
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Simulation of stably stratified turbulent channel flow using residual-based variational multiscale method and isogeometric analysis Comput. Fluids (IF 2.399) Pub Date : 2020-10-16 H. Cen; Q. Zhou; A. Korobenko
Stably stratified turbulent channel flow (STCF) is a canonical flow that is representative of shear-driven boundary mixing processes in geophysical settings. We examine the performance of a turbulence modeling framework composed of residual-based variational multiscale method (RBVMS) and isogeometric analysis (IGA) applied to STCF at friction Reynolds number Reτ=180. The framework is implemented with
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A local correlation-based zero-equation transition model Comput. Fluids (IF 2.399) Pub Date : 2020-10-06 Jatinder Pal Singh Sandhu; Santanu Ghosh
In this work, the local correlation-based one-equation transition model (Menter, F.R., Smirnov, P.E., Liu, T. and Avancha, R., A one-equation local correlation-based transition model. Flow, Turbulence and Combustion, vol. 95, no. 4, pp. 583–619, 2015.) is transformed into a zero-equation transition model. The new model provides an attractive choice in terms of quick implementation of a transition model
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Adjoint-assisted Pareto front tracing in aerodynamic and conjugate heat transfer shape optimization Comput. Fluids (IF 2.399) Pub Date : 2020-10-14 K.T. Gkaragkounis; E.M. Papoutsis-Kiachagias; K.C. Giannakoglou
In this paper, a prediction-correction algorithm, built on the method proposed in [1], uses the adjoint method to trace the Pareto front. The method is initialized by a point on the Pareto front obtained by considering one of the objectives only. During the prediction and correction steps, different systems of equations are derived and solved by treating the Karush-Kuhn-Tucker (KKT) optimality conditions
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An averaging scheme for the efficient approximation of time-periodic flow problems Comput. Fluids (IF 2.399) Pub Date : 2020-10-16 Thomas Richter
We study periodic solutions to the Navier-Stokes equations. The transition phase of a dynamic Navier-Stokes solution to the periodic-in-time state can be excessively long and it depends on parameters like the domain size and the viscosity. Several methods for an accelerated identification of the correct initial data that will yield the periodic state exist. They are mostly based on space-time frameworks
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An enhancement of coupling method for interface computations in incompressible two-phase flows Comput. Fluids (IF 2.399) Pub Date : 2020-10-13 Trong-Nguyen Duy; Van-Tu Nguyen; Thanh-Hoang Phan; Warn-Gyu Park
Coupling techniques that take advantage of the mass conservation property of the volume-of-fluid (VOF) method and the sharpened interface computation of the Level Set (LS) approach are widely used for computations with high accuracy order demands. In this paper, an enhanced coupling method for interface computations in incompressible two-phase flows is presented. In the proposed method, the solution
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A fast transient solver for low-Mach number aerodynamics and aeroacoustics Comput. Fluids (IF 2.399) Pub Date : 2020-10-06 L. Yu; S. Diasinos; B. Thornber
The fractional step method is an efficient time advancement scheme for problems involving transient incompressible flow. The method is desirable over traditional SIMPLE-like algorithms for its non-iterative nature. This paper presents a technique that extends the fractional step method to low-Mach number compressible flow problems. The proposed pressure-velocity coupling and a transient SIMPLEC algorithm
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On the use of optimization techniques for turbulence model calibration Comput. Fluids (IF 2.399) Pub Date : 2020-10-06 Dennis A. Yoder; Paul D. Orkwis
This article discusses the use of numerical optimization procedures to aid in the calibration of turbulence model coefficients. Such methods would increase the rigor and repeatability of the calibration procedure by requiring clearly defined and objective optimization metrics, and could be used to identify unique combinations of coefficient values for specific flow problems. The approach is applied
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A hierarchical parallel implementation for heterogeneous computing. Application to algebra-based CFD simulations on hybrid supercomputers Comput. Fluids (IF 2.399) Pub Date : 2020-10-14 Xavier Álvarez-Farré; Andrey Gorobets; F. Xavier Trias
The quest for new portable implementations of simulation algorithms is motivated by the increasing variety of computing architectures. Moreover, the hybridization of high-performance computing systems imposes additional constraints, since heterogeneous computations are needed to efficiently engage processors and massively-parallel accelerators. This, in turn, involves different parallel paradigms and
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An octree-based immersogeometric approach for modeling inertial migration of particles in channels Comput. Fluids (IF 2.399) Pub Date : 2020-10-21 Songzhe Xu; Boshun Gao; Alec Lofquist; Milinda Fernando; Ming-Chen Hsu; Hari Sundar; Baskar Ganapathysubramanian
In this paper, we develop a scalable, adaptively refined, octree-based finite element approach with immersogeometric analysis to track inertial migration of particles in microchannels. Fluid physics is modeled using a residual-based variational multiscale method, and the particle movement is modeled as rigid body motion. A parallel, hierarchically refined octree mesh is employed as the background mesh
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Data-driven robust state estimation for reduced-order models of 2D boussinesq equations with parametric uncertainties Comput. Fluids (IF 2.399) Pub Date : 2020-10-22 Mouhacine Benosman; Jeff Borggaard
A robust, low-order POD-based state estimator, also known as an observer, for the challenging fluid-dynamics test-case of uncertain 2D Boussinesq equations is presented in this paper. The observer design is based on the methodology recently introduced by the authors1, which incorporates robustness to bounded model uncertainties, and data-driven auto-tuning of the observer gains. An extensive numerical
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Some properties of the Runge-Kutta-Legendre super-time-stepping explicit methods Comput. Fluids (IF 2.399) Pub Date : 2020-10-10 A.S. Dawes
In this paper we will show that the Runge-Kutta-Legendre (RKL) super-time-step methods are built up in stages by combining forward Euler steps with linear extrapolation steps. For second order, we will show that linear interpolation is also used. By using these characteristics a simplified algorithm will be presented. The effect of different types of external boundary conditions are shown. For Neumann
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A five-equation model based global ale method for compressible multifluid and multiphase flows Comput. Fluids (IF 2.399) Pub Date : 2020-10-07 Baolin Tian; Li Li
In this work, a mixing cell closure model was derived in a Lagrangian formulation based on the hypothesis of isentropic compression or expansion. The proposed closure model is used to construct a five-equation model for the simulation of multifluid and multiphase flows. Thereafter a global ALE(Arbitrary Lagrangian-Eulerian) method was developed for the five-equation model. The five-equation based ALE
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Turbulence in realistic geometries with moving boundaries: When simulations meet experiments Comput. Fluids (IF 2.399) Pub Date : 2020-10-10 L. Cappanera; P. Debue; H. Faller; D. Kuzzay; E-W. Saw; C. Nore; J.-L. Guermond; F. Daviaud; C. Wiertel-Gasquet; B. Dubrulle
Considering the current advances in experimental capabilities in fluid mechanics and the advances in computing power and numerical methods in computational fluid mechanics, a question that naturally arises is whether the two sets of techniques are approaching a level of sophistication sufficiently high to deliver results on turbulent flows in realistic geometries that are comparable. The purpose of
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A dual mesh finite domain method for steady-state convection–diffusion problems Comput. Fluids (IF 2.399) Pub Date : 2020-10-09 J.N. Reddy; Matthew Martinez
The dual-mesh finite domain method (DMFDM) proposed by Reddy (2019)[1] is used to study the steady-state convection–diffusion problems in 1D and 2D. In the DMFDM, one mesh of finite elements for the approximation of the domain and primary variables and another mesh of control domains, which also covers the whole domain, to satisfy the governing differential equations are used. The approach is distinguished
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Embedding data analytics and CFD into the digital twin concept Comput. Fluids (IF 2.399) Pub Date : 2020-10-09 Roberto Molinaro; Joel-Steven Singh; Sotiris Catsoulis; Chidambaram Narayanan; Djamel Lakehal
Computer-Aided Engineering (CAE) has supported the industry in its transition from trial-and-error towards physics-based modelling, but our ways of treating and exploiting the simulation results have changed little during this period. Indeed, the business model of CAE centers almost exclusively around delivering base-case simulation results with a few additional operational conditions. In this contribution
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