Improving resource utilization is an important goal of high-performance computing systems of supercomputing centers. To meet this goal, the job scheduler of high-performance computing systems often uses backfilling scheduling to fill short-time jobs into job gaps at the front of the queue. Backfilling scheduling needs to obtain the running time of the job. In the past, the job running time is usually

In unstructured finite volume method, loop on different mesh components such as cells, faces, nodes, etc is used widely for the traversal of data. Mesh loop results in direct or indirect data access that affects data locality significantly. By loop on mesh, many threads accessing the same data lead to data dependence. Both data locality and data dependence play an important part in the performance

A newly developed frosting simulation method, p-VOF method, is applied to simulate the dynamic frost formation on the NACA0012 airfoil under strong convection. The p-VOF method is a pseudo VOF method of the multiphase flow simulation with phase change. By solving a simplified mass conservation equation explicitly instead of the original volume fraction equations in CFD software, the efficiency and

This paper presents numerical studies of the Magnus effect for a kinetic turbine on a horizontal axis. To focus on the Magnus blade, a single self-spinning cylindrical blade is assumed. An iterative direct-forcing immersed boundary method is employed within the Eulerian-Lagrangian framework due to its capability to treat complex and moving geometries. The Eulerian fluid domain is discretized using

The unified stochastic particle method based on the Bhatnagar-Gross-Krook model (USP-BGK) has been proposed recently to overcome the low accuracy and efficiency of the traditional stochastic particle methods, such as the direct simulation Monte Carlo (DSMC) method, for the simulation of multi-scale gas flows. However, running with extra virtual particles and space interpolation, the previous USP-BGK

Correction to: Adv Aerodyn 3, 13 (2021) https://doi.org/10.1186/s42774-021-00066-x After publication of this article [1], it is noticed the article contained some errors. The details are listed below: 1) Page 3: In the sentence ‘ca and cb denote the sound of speed of particles a and b, respectively.’, ‘sound of speed’ should be corrected to ‘speed of sound’. 2) Page 4: In the sentence ‘where ρ0 and

Flow between rotating concentric cylinders, or the Taylor Couette flow, has been studied extensively because of its rich physics, ranging from axisymmetric steady laminar flow, to fully developed turbulent flow. In the present study, we advocate the use of this problem as a benchmark case for scale-resolving simulation, such as large eddy simulation (LES) and direct numerical simulation (DNS). The

A simplified method for calculating the spectral emission of nonequilibrium air plasmas is developed. In order to obtain the nonequilibrium energy level populations, the nonequilibrium coefficients are introduced into the Saha-Boltzmann equation. These nonequilibrium coefficients are calculated by using several significant radiative processes. An approach to the determination of nonequilibrium electronic

In order to visualize the rarefied flow field in a Φ1m hypersonic low-density wind tunnel, an electric glow discharge technique based on high frequency excited power has been developed. Firstly, finite element simulation analysis has been carried out, and it is concluded that the breakdown voltage can be reduced by using high frequency power supply; then an electric glow discharge apparatus has been

The water entry is a classic fluid-structure interaction problem in ocean engineering. The prediction of impact loads on structure during the water entry is critical to some engineering applications. In this paper, a multiphase Riemann-SPH model is developed to investigate water entry problems. In this model, a special treatment, a cut-off value for the particle density, is arranged to avoid the occurrence

In this paper, we present an effective prismatic mesh generation method for viscous flow simulations. To address the prismatic mesh collisions in recessed cavities or slit areas, we exploit 3D tensors controlled anisotropic volume harmonic field to generate prismatic meshes. Specially, a well-fitting tetrahedral mesh is first constructed to serve as the discrete computation domain of volume harmonic

Correction to: Adv Aerodyn 3, 8 (2021) https://doi.org/10.1186/s42774-020-00060-9 After publication of this article [1], it is noticed letter ‘a’ is missing from the below sentence in section 6.2 ‘Adding stretching components’: The subscript “ ” means “adding” the stretching components. The correct sentence should be: The subscript “a” means “adding” the stretching components. The original article

A scaled model of the X38-like configuration was simulated under hypersonic conditions for the direct simulation Monte Carlo method and the unified gas kinetic scheme. The inflow conditions considered several flow regimes, from the near-continuum through the slip-transitional to the free molecular regime. Flow fields and surface properties were compared in detail between these two methods. Not only

In this paper, we extend the unified gas-kinetic wave-particle (UGKWP) methods to the multi-species gas mixture and multiscale plasma transport. The construction of the scheme is based on the direct modeling on the mesh size and time step scales, and the local cell’s Knudsen number determines the flow physics. The proposed scheme has the multiscale and asymptotic complexity diminishing properties.

The newly developed vortex-identification method, Liutex, has provided a new systematic description of the local fluid rotation, which includes scalar, vector, and tensor forms. However, the advantages of Liutex over the other widely used vortex-identification methods such as Q, ∆, λ2, and λci have not been realized. These traditional methods count on shearing and stretching as a part of vortex strength

At present, the control capability of dielectric barrier discharge (DBD) plasma actuation covers the flow velocity range of helicopter’s retreating blades, so it is necessary to extend it to the dynamic stall control of rotor airfoils. A DBD plasma actuator was adopted to control the dynamic stall of an oscillating CRA309 airfoil in this paper. The effectiveness of alternating current (AC) DBD plasma

Multiscale gas flows appear in many fields and have received particular attention in recent years. It is challenging to model and simulate such processes due to the large span of temporal and spatial scales. The discrete unified gas kinetic scheme (DUGKS) is a recently developed numerical approach for simulating multiscale flows based on kinetic models. The finite-volume DUGKS differs from the classical

In this paper, based on simplified Boltzmann equation, we explore the inverse-design of mesoscopic models for compressible flow using the Chapman-Enskog analysis. Starting from the single-relaxation-time Boltzmann equation with an additional source term, two model Boltzmann equations for two reduced distribution functions are obtained, each then also having an additional undetermined source term. Under

In this era of fast-depleting natural resources, the hike in fuel prices is ever-growing. With stringent norms over environmental policies, the automotive manufacturers are on a voyage to produce efficient vehicles with lower emissions. High-speed cars are at a stake to provide uncompromised performance but having strict rules over emissions drives the companies to approach through a different route

With the increasing of computing ability, large-scale simulations have been generating massive amounts of data in aerodynamics. Sort-last parallel rendering is the most classical image compositing method for large-scale scientific visualization. However, in the stage of image compositing, the sort-last method may suffer from scalability problem on large-scale processors. Existing image compositing

The effectiveness of the Vectored Thrust Ducted Propeller (VTDP) system is not high currently, especially the lateral force is not large enough. Thus, a conceptual design for a deflection device of a VTDP system was proposed to achieve effective hovering control. The magnitude of the lateral force that was applied to maintain balance while hovering was examined. A comparison between the experimental

A high-order accurate reconstructed discontinuous Galerkin (rDG) method is developed for compressible inviscid and viscous flows in arbitrary Lagrangian-Eulerian (ALE) formulation on moving and deforming unstructured curved meshes. Taylor basis functions in the rDG method are defined on the time-dependent domain, where the integration and computations are performed. The Geometric Conservation Law (GCL)

Properties of wall pressure beneath a transitional hypersonic boundary layer over a 7∘ half-angle blunt cone at angle of attack 6∘ are studied by Direct Numerical Simulation. The wall pressure has two distinct frequency peaks. The low-frequency peak with f≈10−50 kHz is very likely the unsteady crossflow mode based on its convection direction, i.e. along the axial direction and towards the windward

The evacuated tube transportation has great potential in the future because of its advantages of energy saving and environmental protection. The train runs in the closed tube at ultra-high speed. The heat quantity generated by aerodynamic heating is not easy to spread to external environment and then accumulates in the tube, inducing the ambient temperature in the tube to rise gradually. In this paper

The computation of compressible flows at all Mach numbers is a very challenging problem. An efficient numerical method for solving this problem needs to have shock-capturing capability in the high Mach number regime, while it can deal with stiffness and accuracy in the low Mach number regime. This paper designs a high order semi-implicit weighted compact nonlinear scheme (WCNS) for the all-Mach isentropic

In this paper, we introduce the discrete Maxwellian equilibrium distribution function for incompressible flow and force term into the two-stage third-order Discrete Unified Gas-Kinetic Scheme (DUGKS) for simulating low-speed turbulent flows. The Wall-Adapting Local Eddy-viscosity (WALE) and Vreman sub-grid models for Large-Eddy Simulations (LES) of turbulent flows are coupled within the present framework

Accuracy of unstructured finite volume discretization is greatly influenced by the gradient reconstruction. For the commonly used k-exact reconstruction method, the cell centroid is always chosen as the reference point to formulate the reconstructed function. But in some practical problems, such as the boundary layer, cells in this area are always set with high aspect ratio to improve the local field

For internal flow with supersonic inflow boundary conditions, a complicated oblique shock reflection may occur. Different from the planar shock reflection problem, where the shape of the incident shock can be a straight line, the shape of the incident shock wave in the inward-facing axisymmetric shock reflection in steady flow is an unknown curve. In this paper, a simple theoretical approach is proposed

This paper presents a robust sharp-interface immersed boundary method for simulating inviscid compressible flows over stationary and moving bodies. The flow field is governed by Euler equations, which are solved by using the open source library OpenFOAM. Discontinuities such as those introduced by shock waves are captured by using Kurganov and Tadmor divergence scheme. Wall-slip boundary conditions

An amendment to this paper has been published and can be accessed via the original article.

The flow regime of micro flow varies from collisionless regime to hydrodynamic regime according to the Knudsen number Kn, which is defined as the ratio of the mean free path over the local characteristic length. On the kinetic scale, the dynamics of a small-perturbed micro flow can be described by the linearized kinetic equation. In the continuum regime, according to the Chapman-Enskog theory, hydrodynamic

The high enthalpy nozzle converts the high enthalpy stagnation gas into the hypervelocity free flow. The flow region of the high enthalpy nozzle consists of three parts: an equilibrium region upstream of the throat, a non-equilibrium region near the throat, and a frozen region downstream of the throat. Here we propose to consider the thermochemical non-equilibrium scale effects in the high enthalpy

Nearly all illuminating classic hypersonic flow theories address aerodynamic phenomena as a perfect gas in the high-speed range and at the upper limit of continuum gas domain. The hypersonic flow is quantitatively defined by the Mach number independent principle, which is derived from the asymptotes of the Rankine-Hugoniot relationship. However, most hypersonic flows encounter strong shock-wave compressions

Since the classical weighted essentially non-oscillatory (WENO) scheme is proposed, various improved versions have been developed, and a typical one is the WENO-Z scheme. Although better resolution is achieved, it is shown in this article that, the result of WENO-Z scheme suffers evident distortion in the long-time simulation of the linear advection equation. In order to fix the problem of WENO-Z,

In this paper, we present a hybrid grid generation approach for viscous flow simulations by marching a surface triangulation on viscous walls along certain directions. Focuses are on the computing strategies used to determine the marching directions and distances since these strategies determine the quality of the resulting elements and the reliability of the meshing procedure to a large extent. With

Noise prediction from streamlined bodies such as wind turbine blades can be predicted accurately using CFD computations that use spatio-temporal turbulence models at the expense of high computational power. In this work, empirical methods proposed from BPM, Grosveld and Lowson are used to compute numerically to analyse the influence of rotor solidity factor on broadband trailing edge noise from a 2 MW

An amendment to this paper has been published and can be accessed via the original article.

Large Eddy Simulations are carried out to analyze flow past flat plate in different configurations and inclinations. A thin flat plate is considered at three inclination angles (α = 30°, 60° and 90°) and three aspect ratios (AR = 0.5, 2 and 5). The Reynolds number based on the free stream velocity and chord length of the plate at different inclination angles varies between 75,000 to 150,000. An increase

A truly three-dimensional (3D) gas-kinetic flux solver for simulation of incompressible and compressible viscous flows is presented in this work. By local reconstruction of continuous Boltzmann equation, the inviscid and viscous fluxes across the cell interface are evaluated simultaneously in the solver. Different from conventional gas-kinetic scheme, in the present work, the distribution function

The flow of an active thermal protection system exploiting subsonic counter-flow jets for wing leading edges of hypersonic vehicles is numerically studied on the basis of the three dimensional Navier-Stokes equations. The coolant air issuing from around the stagnation point as an array of three jets spreads over both the upper and the lower sides of the cylinder surface and about 40 ~ 60% cooling effectiveness

We investigate the gas flows near to solid surfaces in terms of the local spatial variation in the molecular mean free path (MFP). Molecular dynamics (MD) is the appropriate scientific tool for obtaining molecularly-accurate dynamic information in micro and nano-scale gas flows, and has been used to evaluate the molecular mean free path of gases. In the calibration procedure, the viscosity of a gas

Advanced sensing techniques are in big demand for applications in hypersonic wind tunnel harsh environments, such as aero(thermo)dynamics measurements, thermal protection of aircraft structures, air-breathing propulsion, light-weighted and high-strength materials, etc. In comparison with traditional electromechanical or electronic sensors, the fiber optic sensors have relatively high potential to work

The unsteady transonic aerodynamics of a wing-body configuration is investigated by solving the Unsteady Reynolds-averaged Navier-Stokes equations closed with the full Reynolds Stress Model. This work presents the prediction of flow field characteristics during deep shock-buffet penetration of a transport aircraft-representative geometry. Mach number of 0.85, and Reynolds number of 5 million based

Blunt-body configurations are the most common geometries adopted for non-lifting re-entry vehicles. Hypersonic re-entry vehicles experience different flow regimes during flight due to drastic changes in atmospheric density. The conventional Navier-Stokes-Fourier equations with no-slip and no-jump boundary conditions may not provide accurate information regarding the aerothermodynamic properties of

The DSMC modeling is developed to simulate three-dimensional (3D) rarefied ionization flows and numerically forecast the communication blackout around spacecraft during hypervelocity reentry. A new weighting factor scheme for rare species is introduced, whose key point is to modify the corresponding chemical reaction coefficients involving electrons, meanwhile reproduce the rare species in resultants

Currently available procedures of electron temperature calculations in studying ionized flows around reentry spacecraft by the direct simulation Monte Carlo (DSMC) method are analyzed. It is shown that the heat conduction of electrons is not taken into account in these procedures. The contributions of various effects to the electron energy balance are calculated by an example of the RAM-C II capsule

Recently, a novel concept of flapping Micro-Air-Vehicles (FMAVs) with four wings has been proposed, which potentially utilizes the clap-and-fling effect for lift enhancement and agile maneuvers through an adjustment of wing kinematics. However, the application of the clap-and-fling effect in the four-winged FMAVs is underexplored and the dynamic stability is still unclear. In this paper, aerodynamics

Despite over fifty years of research on shock wave boundary layer effects and interactions, many related technical issues continue to be controversial and debated. The present survey provides an overview of the present state of knowledge on such effects and interactions, including discussions of: (i) general features of shock wave interactions, (ii) test section configurations for investigation of

In this work, a discrete unified gas kinetic scheme (DUGKS) is developed for radiative transfer in anisotropic scattering media. The method is an extension of a previous one for isotropic radiation problems [1]. The present scheme is a finite-volume discretization of the anisotropic gray radiation equation, where the anisotropic scattering phase function is approximated by the Legendre polynomial expansion

Many macroscopic equations are proposed to describe the rarefied gas dynamics beyond the Navier-Stokes level, either from the mesoscopic Boltzmann equation or some physical arguments, including (i) Burnett, Woods, super-Burnett, augmented Burnett equations derived from the Chapman-Enskog expansion of the Boltzmann equation, (ii) Grad 13, regularized 13/26 moment equations, rational extended thermodynamics

Cryogenic wind tunnel is a sophisticated aerodynamics ground test facility, which operates in cryogenic temperature with injection of liquid nitrogen. The multi-variable, nonlinear and coupled dynamics existing between the temperature, pressure and Mach number in the tunnel, poses great challenges for the effective control of the tunnel. L1 adaptive control is a new control methodology developed in

A high-order Navier-Stokes solver based on the flux reconstruction (FR) or the correction procedure via reconstruction (CPR) formulation is employed to perform a direct numerical simulation (DNS) and large eddy simulations (LES) of a well-known benchmark problem – transitional flow over the low-pressure T106C turbine cascade. Hp-refinement studies are carried out to assess the resolution requirement

A three-dimensional-membrane-type wing is investigated applying fluid-structure-interaction computations and complementary experiments. An analysis for three Reynolds numbers is conducted at various angles of attack. The computations are performed by means of the TAU-Code and the FEM Carat++ solver. Wind-tunnel tests are carried out for performance analysis and to estimate the accuracy of the computations

We have studied the transformation process from primary instabilities to secondary instabilities with direct numerical simulations and stability theories (Spatial Biglobal and plane-marching parabolized stability equations) in detail. First Mack mode and second Mack mode are shown to be able to evolve into the sinuous mode and the varicose mode of secondary instability, respectively. Although the characteristics

The accuracy of gradient reconstruction methods on unstructured meshes is analyzed both mathematically and numerically. Mathematical derivations reveal that, for gradient reconstruction based on the Green-Gauss theorem (the GG methods), if the summation of first-and-lower-order terms does not counterbalance in the discretized integral process, which rarely occurs, second-order accurate approximation

The numerical methods for computing the stability derivatives of the aircraft by solving unsteady sensitivity equations which was proposed in our previous papers was extended to solve three-dimensional problems in this paper. Both the static and dynamic derivatives of the hypersonic blunt cone undergoing pitching oscillation around a fixed point were computed using the new methods. The predicted static

Weighted essentially non-oscillatory (WENO) schemes are a class of high-order shock capturing schemes which have been designed and applied to solve many fluid dynamics problems to study the detailed flow structures and their evolutions. However, like many other high-order shock capturing schemes, WENO schemes also suffer from the problem that it can not easily converge to a steady state solution if

For the general case of a spatial isoenergetic flow of ideal gas, Helmholtz’s theorems are generalized and the speed with which vortex tubes move is found, keeping the intensity. It is shown that along the streamline without stagnation point, vorticity either is equal to zero everywhere, or it is non zero at all. The pattern of vortex lines behind the three-dimensional detached bow shock wave is specified

The paper presents the experimental results and the results of direct numerical simulation of the development and interaction of two wave trains from two point sources of controlled disturbances in a supersonic boundary layer on a flat plate with an incident flow Mach number of 2.5. Sources were located parallel to the leading edge of the model. For the introduction of controlled disturbances into

In this paper, a class of compact higher-order gas-kinetic schemes (GKS) with spectral-like resolution will be presented. Based on the high-order gas evolution model, both the flux function and conservative flow variables in GKS can be evaluated explicitly from the time-accurate gas distribution function at a cell interface. As a result, inside each control volume both the cell-averaged flow variables