The accuracy of Reynolds-averaged Navier-Stokes results for turbulent scalar transport are affected by epistemic uncertainty in the Reynolds stress model in two ways: by altering the mean velocity field that advects the scalar, and by altering the inputs required for scalar flux models. We investigate these effects by propagating uncertainty in the Reynolds stress model to the prediction of scalar

The assumptions that form the basis for Reynolds stress closure models have been formulated by considering canonical flows. As a result, the accuracy of Reynolds-averaged Navier–Stokes simulations can deteriorate significantly when modeling complex flows, and engineering applications would benefit from methods that can quantify the corresponding uncertainty in the predictions. This paper analyzes the

We proposed a predictor-corrector algorithm for the hourglass control in Lagrangian hydrodynamics. The main idea of the algorithm is utilizing the subzonal density variation as the indicator of the degree of hourglass distortion and the pseudo time evolution in the velocity field as the filter of the hourglass motion. The algorithm can be regarded as an enhancement of the existing hourglass control

In this paper we provide bound estimates for the two fastest wave speeds emerging from the solution of the Riemann problem for three well-known hyperbolic systems, namely the Euler equations of gas dynamics, the shallow water equations and the blood flow equations for arteries. Several approaches are presented, all being direct, that is non-iterative. The resulting bounds range from crude but simple

For the first time, a set of Lattice-Boltzmann two-way coupling pointwise Euler-Lagrange models is applied to gas mixing of sludge for anaerobic digestion. The set comprises a local model, a “first-neighbour” (viz., back-coupling occurs to the voxel where a particle sits, plus its first neighbours) and a “smoothing-kernel” (forward- and back-coupling occur through a smoothed-kernel averaging procedure)

We consider implicit time-marching schemes for the compressible Navier-Stokes equations, discretised using the Discontinuous Galerkin Spectral Element Method with Gauss-Lobatto nodal points (GL-DGSEM). We compare classic implicit strategies for the full Jacobian system to our recently developed static condensation technique for GL-DGSEM Rueda-Ramírez et al.(2019), A Statically Condensed Discontinuous

Present study proposes a methodology and provides computational results for a conjugate heat transfer problem, where one would like to level out the temperature along the solid-fluid interface. Such constraints or needs may emerges in industrial processes such as mold casting and efficient heat exchanger design. In order to describe the methodology, we consider a benchmark problem of heat and mass

The software package Volna-OP2 is a robust and efficient code capable of simulating the complete life cycle of a tsunami whilst harnessing the latest High Performance Computing (HPC) architectures. In this paper, a comprehensive error analysis and scalability study of the GPU version of the code is presented. A novel decomposition of the numerical errors into the dispersion and dissipation components

In this paper, the Barely Implicit Correction (BIC) algorithm is applied to the simulation of low-Mach-number, reactive flows. The BIC algorithm is a solution procedure consisting of an explicit predictor step to solve the convective portion of the Navier-Stokes equations and an implicit corrector step which removes the acoustic limit on the integration time step. We show how to include reaction processes

A new 3D multiphase numerical capability is presented here for simulating multiphase flow regimes at all Mach numbers (M). The new method is a semi-implicit extension of the finite volume discrete equation method (DEM) of Chinnaya et al. (2004), which originally used explicit time-stepping. The capability is also developed to work with another extension of the DEM to moving grids for arbitrary Lagrangian-Eularian

We propose an interface-sharpening method for volume-of-fluid simulations of two-phase compressible flows. In the proposed method, sharpening of the interface between two phases is achieved by introducing a source term to the advection-reaction equation for the phase volume fraction. The inherent numerical diffusivity arising from the discretization of this equation is used to construct the source

It is necessary to accurately predict the diffusion and deposition range of a large amount of sand dumped from a hopper barge for efficient reclamation in a coastal area. Many previous studies have proposed useful models to simulate the diffusion behavior of sand in fluid; however, most of their models have not considered the deposition of sand. This study proposes a particle-based numerical model

For modeling turbulent flow, the near-wall domain decomposition (NDD) approach initially proposed by the second author and recently developed in a number of papers proved to be very efficient. It leads to a non-overlapping domain decomposition with a Robin-to-Dirichlet map between an inner (near-wall) and outer regions. The regions are linked with each other via interface boundary conditions of Robin

We present an adaptive well-balanced positivity preserving central-upwind scheme on quadtree grids for shallow water equations. The use of quadtree grids results in a robust, efficient and highly accurate numerical method. The quadtree model is developed based on the well-balanced positivity preserving central-upwind scheme proposed in [A. Kurganov and G. Petrova, Commun. Math. Sci., 5 (2007), pp.

The lattice Boltzmann (LB) method has gained much success in a variety of fields involving fluid flow and/or heat transfer. In this method, the bounce-back scheme is a popular technique for the treatment of nonslip boundaries. However, this scheme leads to a staircase representation of curved walls. Therefore many curved boundary schemes have been proposed, but mostly have detrimental effects such

In this paper, a spectral element method for the solution of the two-dimensional transient incompressible Navier-Stokes equations is introduced, which combines the segregated velocity-pressure equal-order formulation originated from the SIMPLE (semi-implicit method for pressure linked equations) algorithm. In contrast to previous segregated finite element method based on the SIMPLE algorithm, the pressure

Several nonlinear model reduction techniques are compared for the three cases of the non-parallel version of the Kuramoto-Sivashinsky equation, the transient regime of flow past a cylinder at Re=100 and fully developed flow past a cylinder at the same Reynolds number. The linear terms of the governing equations are reduced by Galerkin projection onto a POD basis of the flow state, while the reduced

Insight into the effects of motions and waves on a ship airwake can be used to provide information regarding safe conditions for at sea flight operations and pilot training. We present a study on the effects of waves and motions on a ship's airwake and a helicopter operating above the flight deck using full scale computational fluid dynamics simulations. The ONR Tumblehome Ship (ONRT) geometry is analyzed

In this article, a new 6th-order weighted essentially non-oscillatory (WENO) scheme is developed. As with previous 6th-order central-upwind WENO schemes, the present scheme is a convex combination of four candidate linear reconstructions. The difference is that the most upwind and downwind stencils use four cell values, while the inner two stencils nominally use three cell values but the original quadratic

An explicit 3D Reynolds Averaged Navier-Stokes solver SURFS3D has been developed and run on a structured grid. A 4-stage Runge-Kutta (RK) method is used for the time integration and OpenMP is used to parallelize the solver. This is used as a platform to compare Van Leer’s Flux Vector Splitting Method (VLFVSM) to a variant of Liou’s Advection Upstream Splitting with velocity and pressure diffusion (AUSM

The entropy-conservative/stable, curvilinear, nonconforming, p-refinement algorithm for hyperbolic conservation laws of Del Rey Fernández et al. (2019) is extended from the compressible Euler equations to the compressible Navier–Stokes equations. A simple and flexible coupling procedure with planar interpolation operators between adjoining nonconforming elements is used. Curvilinear volume metric terms

In this paper, we consider the capabilities of the Boltzmann equation with the Shakhov or ellipsoidal models for the collision term to capture the characteristics of rarefied gas flows. The benchmark is performed by comparing the results obtained using these kinetic model equations with direct simulation Monte Carlo (DSMC) results for particles interacting via ab initiopotentials. The analysis is restricted

A novel iterative direct-forcing immersed boundary (IB) method, which meets the divergence-free and no-slip conditions simultaneously, is proposed in the finite element framework for incompressible flow problems. The coupled velocity and the pressure of the fluid field are solved by the Characteristic-based Split scheme. The formulation for the extra body force is derived according to the no-slip boundary

SLAU2 (Simple Low-dissipation Advection-Upstream-splitting-method 2) numerical flux function, one of AUSM-type methods (3-wave solver), originally developed and widely used in gasdynamics, has been applied to two-dimensional magnetohydrodynamics (MHD) simulations. According to numerical tests for a wide range of flow and magnetic conditions, its reliability, efficiency, and accuracy have been demonstrated:

Different variable resolution turbulence modelling approaches (Hybrid, Bridging models and LES) are evaluated for turbulent channel flow at Reτ=395, for cases using streamwise periodic boundary conditions and a synthetic turbulence generator. The effect of iterative, statistical and discretisation errors is investigated. For LES, little difference between the different sub-filter modelling approaches

In this paper we propose tools for high-order mesh optimization and demonstrate their benefits in the context of multi-material Arbitrary Lagrangian-Eulerian (ALE) compressible shock hydrodynamic applications. The mesh optimization process is driven by information provided by the simulation which uses the optimized mesh, such as shock positions, material regions, known error estimates, etc. These simulation

For satellite design engineers, an exhaust plume from a liquid rocket engine has been classified as a potential source of local heat load and surface contamination on payload sensors or equipment because several kinds of chemical species at relatively high temperatures can severely impact on the performance of optically-sensitive components. Hence, an accurate prediction of plume influence on a given

This study focuses on the development of a theoretical framework and corresponding algorithms to establish surrogate models for multiphase flow processes using Gaussian process (GP)-based machine learning technique trained by high-fidelity simulation data. The training (and testing) datasetsare obtained by solving three-dimensional, incompressible, variable-density and viscosity conservation equations

The discontinuous Galerkin (DG) method is a promising numerical method to enable high- order simulations of turbulent flows associated with complex geometries. The method allows implicit large eddy simulations, however affordable simulations of very high Reynolds’ number flows require wall models. In addition, high Reynolds’ number typically implies the simulations are under-resolved. This becomes

Diverse transport problems, especially those based on fluid flow models, are intrinsically multiscale and nonlinear, characteristics that often lead to intricate dynamics such as the development of instabilities and turbulence. Computational simulations that resolve all scales in these problems are often unfeasible, prompting to coarse-grained simulation strategies in which small-scale features are

A parametric, hybrid reduced order method based on the Proper Orthogonal Decomposition with both Galerkin projection and interpolation based on Radial Basis Functions method is presented. This method is tested on a case of turbulent non-isothermal mixing in a T-junction pipe, a common flow arrangement found in nuclear reactor cooling systems. The reduced order model is derived from the 3D unsteady

Discrete modeling of particle-fluid interaction was of great importance for its wide applications in chemical, petroleum and geotechnical engineering. Using Immersed Boundary Method (IBM) to couple Discrete Element Method (DEM) with Lattice Boltzmann Method (LBM) was adopted by many researchers to study particle-fluid systems. However, to accurately simulate the behavior of a large number of particles

In this article we present a 1D single-material conservative remapping method that relies on high accurate reconstructions: polynomial (P4, P1 with slope limiter) and non-linear hyperbolic tangent (THINC) representations. Such remapping procedure is intended to be used pairwise with a cell-centered Lagrangian scheme along with a rezone strategy to build a so-called indirect Arbitrary-Lagrangian-Eulerian

Rayleigh-Taylor instability RTI occurs while a less dense fluid is accelerating a denser one Rayleigh and Strutt (1983); Taylor (1950)[1,2]. Under gravity the material strength damps and prevents RTI formation in solids. However, at higher accelerations RTI will prevail. The Staggered Mesh Godunov (SMG) scheme for Lagrangian Luttwak and Falcovitz (2006)[3] and ALE Luttwak and Falcovitz (2005)[4] hydrodynamics

Nonlocal models provide accurate representations of physical phenomena ranging from fracture mechanics to complex subsurface flows, settings in which traditional partial differential equation models fail to capture effects caused by long-range forces at the microscale and mesoscale. However, the application of nonlocal models to problems involving interfaces, such as multimaterial simulations and fluid-structure

Modeling the effect of complex terrain on high Reynolds number flows is important to improve our understanding of flow dynamics in wind farms and the dispersion of pollen and pollutants in hilly or mountainous terrain as well as the flow in urban areas. Unfortunately, simulating high Reynolds number flows over complex terrain is still a big challenge. Therefore, we present a simplified version of the

The extension of the 3D cell-centered Finite Volume EUCCLHYD scheme to the hyperelasticity system is proposed here. This study is based on the left Cauchy-Green tensor B which enables to work in a fully updated Lagrangian formalism. The second order extension of this scheme is proposed using a MUSCL (Monotonic Upstream-centered Scheme for Conservation Laws) procedure combined with a GRP (Generalized

In “Solution Property Reconstruction for Finite Volume scheme: a BVD+MOOD framework”, Int. J. Numer. Methods Fluids, 2020, we have designed a novel solution property preserving reconstruction, so-called multi-stage BVD-MOOD scheme. The scheme is able to maintain a high accuracy in smooth profile, eliminate the oscillations in the vicinity of discontinuity, capture sharply discontinuity and preserve

In this paper, we propose an arbitrary Lagrangian Eulerian (ALE) method for solving compressible multi-material flows on two-dimensional adaptive unstructured triangular meshes. We couple a conservative equation related to a γ-model (or a mass fractional model) with the system of fluid equations for obtaining the specific heat ratio of the multi-material flows. The discretization of the coupling system

We extend a higher-order finite volume cell-centered hydrodynamic (CCH) formulation to include an interface-aware subscale closure model and a multi-material remap for simulating 3D compressible hydrodynamic problems within an arbitrary Lagrangian-Eulerian (ALE) framework. This CCH formulation involves a multidirectional approximate Riemann solution using quadratic polynomial reconstructions of the

The hybridization of the fourth-order central scheme and a third-order WENO (weighted essentially non-oscillatory) scheme aims to obtain fourth-order accuracy in smooth regions and keep ENO property near shock waves. However, according to our numerical tests, such existing hybrid schemes may generate spurious waves near shocks. To overcome this problem, in this paper, a new two-step method is proposed

Roe solver is one of the most popular upwind schemes in computational fluid dynamics which is first-order accurate in space. However, the amount of numerical dissipation gets larger than necessary for high order numerical schemes and then becomes the dominant term of the numerical error. This paper proposes a modified Roe solver that can use high order schemes with high stability based on splitting

This work presents a robust and efficient sharp interface immersed boundary (IBM) framework, which is applicable for all-speed flow regimes and is capable of handling arbitrarily complex bodies (stationary or moving). The work deploys an in-house, parallel, multi-block structured finite volume flow solver, which employs a 3D unsteady Favre averaged Navier Stokes equations in a generalized curvilinear

Computational fluid dynamics and aerodynamics, which complement more expensive empirical approaches, are critical for developing aerospace vehicles. During the past three decades, computational aerodynamics capability has improved remarkably, following advances in computer hardware and algorithm development. However, for complex applications, the demands on computational fluid dynamics continue to

The apparent gas permeability (AGP) of a porous medium is an important parameter to predict production of unconventional gas. The Klinkenberg correlation, which states that the ratio of the AGP to the intrinsic permeability is approximately a linear function of reciprocal mean gas pressure, is one of the most popular estimations to quantify AGP. However, due to the difficulty in defining the characteristic

In various industrial combustion devices, such as liquid rocket engines at ignition or Diesel engines during the compression stage, the operating point varies over a wide range of pressures. These pressure variations can lead to a change of thermodynamic regime when the critical pressure is exceeded, switching from two-phase injection to transcritical injection. Such change modifies the topology of

A two-phase model and its application to wavefields numerical simulation are discussed in the context of modeling of compressible fluid flows in elastic porous media. The derivation of the model is based on a theory of thermodynamically compatible systems and on a model of nonlinear elastoplasticity combined with a two-phase compressible fluid flow model. The governing equations of the model include

A low-diffusion self-adaptive flux-vector splitting method is presented for the Euler equations. The flux-vector is here split into convective and acoustic parts following the formulation recently proposed by the authors. This procedure is based on the Zha-Bilgen (or previously Baraille et al. for the Euler barotropic system) approach enriched by a dynamic flow-dependent splitting parameter based on

The aim of the present work is to progress in the identification of the effects responsible for the formation of jets in heterogeneous gas-particle cylindrical and spherical explosions. In this direction three two-phase flow models are considered, namely Baer and Nunziato’s (BN) (1986) model, Marble’s (1963) model and the dense-dilute model of Saurel et al. (2017). The first and third ones involve

To accurately model inviscid flow with shock waves using staggered-grid Lagrangian hydrodynamics, artificial viscosity is introduced to convert kinetic energy into internal energy, thereby providing a mechanism to generate the required entropy increase across shocks. In this paper, we propose a new method for constructing an adaptive, artificial viscosity in the context of one-dimensional, staggered-grid

We present a multi-material cell model (closure model) for demanding arbitrary Lagrangian-Eulerian (ALE) simulations of fluids and solids. It is based on the interface-aware sub-scale dynamics (IASSD) approach which utilizes the exact material interface geometry within the computational cell to calculate internal material interactions. Our formulation of the closure model also aims to improve the accuracy

An explicit high-order semi-Lagrangian method is developed for the solution of Lagrangian transport equations in Eulerian-Lagrangian formulations. The method is consistent with an explicit, discontinuous spectral element method (DSEM) discretization of the Eulerian formulation. The semi-Lagrangian method seeds particles at Gauss quadrature collocation nodes within a spectral element. The particles

This work studies the parallelization and empirical convergence of two finite difference acoustic wave propagation methods on 2-D rectangular grids, that use the same alternating direction implicit (ADI) time integration. This ADI integration is based on a second-order implicit Crank-Nicolson temporal discretization that is factored out by a Peaceman-Rachford decomposition of the time and space equation

Dynamic mesh adaptation methods require suitable refinement indicators. In the absence of a comprehensive error estimation theory, adaptive mesh refinement (AMR) for nonlinear hyperbolic conservation laws, e.g. compressible Euler equations, in practice utilizes mainly heuristic smoothness indicators like combinations of scaled gradient criteria. As an alternative, we describe in detail an easy to implement

The work focuses on the calibration of cavitation model parameters for the numerical simulation of three-phase injector flows. Cavitation is modeled through a transport equation for the void fraction closed by the Schnerr-Sauer relation. The vaporization and condensation factors contained in this model are considered for calibration against experimental data available for a test-case characterized

In this paper, we are concerned with the study of efficient and high order accurate numerical methods for solving Hamilton-Jacobi (HJ) equations with initial conditions defined in the whole domain. One of the commonly used strategy is to solve the problem only in a finite domain, but the determination of boundary conditions at the artificial boundary of the finite computational domain is a problem

Aquarium tests of cylindrical high-explosive charges provide optical data of the detonation front velocity and shape, propagation of the shock wave in the surrounding water, and expansion rates of the detonation products behind the front. Data from aquarium experiments is often used for calibration of reactive burn models based on phenomenological equations of state (EOS) and reaction rate laws. This

The numerical approximation of compressible hydrodynamics is at the core of high-energy density (HED) multiphysics simulations as shocks are the driving force in experiments like inertial confinement fusion (ICF). In this work, we describe our extension of the hyperviscosity technique, originally developed for shock treatment in finite difference simulations, for use in arbitrarily high-order finite

Sting vibrations in hypersonic wind tunnel data are investigated and modeled to show how pressure fluctuations are affected. This is in contrast with lower-speed flow where the sting's resonant frequencies are simply superimposed upon the data, leading to their simple removal, either with notch (band-stop) filtering or long-run averaging. The fundamental flow alteration at hypersonic velocities, as

The present work concerns the inference of the coefficients of fluid-dependent thermodynamic models, applicable to complex molecular compounds with non-ideal effects. The main objective is to numerically assess the potential of using experimental measurements of some expansion flows to infer the model parameters. The Bayesian formulation incorporates uncertainties in the flow conditions and measurement