# B. BasaraAVL LIST GMBH · Advanced Simulation Technologies

B. Basara

PhD

## About

178

Publications

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1,409

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Introduction

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May 1995 - January 2019

January 1995 - January 2019

## Publications

Publications (178)

This paper presents calculations of external car aerodynamics by using the finite volume (FV) immersed-boundary method. The FV numerical codes primarily employ Reynolds-Averaged Navier-Stokes (RANS) models. In recent years, and due to possibility to run very large computational meshes, these models are usually used in conjunction with the advanced...

The feasibility of a recently developed eddy-resolving model of turbulence, termed as Very LES (Large-Eddy-Simulation), was tested by simulating the flow dynamics in two moving piston-cylinder assemblies. The first configuration deals with the compression of a tumbling vortex generated during the intake process within a cylinder with the square cro...

A cell-centered finite volume method with the Soner boundary condition is proposed to compute the signed distance function from a given surface in general three-dimensional (3D) computational domains discretized by polyhedral cells. The governing equation is the bidirectional time-relaxed eikonal equation and the proposed numerical method is based...

A flow simulation was developed to understand the flow surrounding a train that was passing through a tornado and the resulting aerodynamic forces acting on the vehicle. Unsteady Reynolds averaged Navier–Stokes equations were solved to reproduce a previously-conducted laboratory experiment, in which a model train runs through a stationary tornado-l...

An LES (large eddy simulation) investigation at = 8 × 10 4 has been conducted to predict the flow past a simplified frigate shape model at yaw, of which the stern is analogous to a double backward-facing step. At 0 • yaw, the occurrence of a double bi-stable flow configuration is recorded, i.e. an asymmetrical flow topology is observed behind each...

At present, when solving problems of hydrodynamics of viscous incompressible and compressible flows in conditions of complex geometry with moving elements, preference is often given to meshless numerical algorithms based on the Smoothed Particle Hydrodynamics (SPH). We have developed our own parallel SPH algorithm that uses graphic processors to so...

The real-gas analytical equation of state (EoS) for nitrogen is developed. The applicability domain of the EoS is verified in a wide range of density (from 0 to the value at the triple point, 0.867 g/cm3) and temperature (from 100 to 5000 K). The obtained EoS is introduced into the gasdynamic code for calculating multidimensional turbulent reactive...

A cell-centered finite volume method is used to numerically solve a regularized mean curvature flow equation on polyhedral meshes. It is based on an over-relaxed correction method used previously for linear diffusion problems. An iterative nonlinear Crank-Nicolson method is proposed to obtain the second-order accuracy in time and space. The propose...

This paper presents calculations of engine flows by using the Partially-Averaged Navier Stokes (PANS) method (Girimaji [1]; [2]). The PANS is a scale-resolving turbulence computational approach designed to resolve large scale fluctuations and model the remainder with appropriate closures. Depending upon the prescribed cut-off length (filter width)...

The objective of this article is to briefly review the progress in Partially Averaged Navier-Stokes (PANS) method over the last fifteen years. We first present the foundational concepts of the PANS approach and proceed to exhibit some of the key simulation results in important engineering flows. PANS provides a mathematical framework and the physic...

The objective of this article is to briefly review the progress in Partially Averaged Navier-Stokes (PANS) method over the last fifteen years. We first present the foundational concepts of the PANS approach and proceed to exhibit some of the key simulation results in important engineering flows. PANS provides a mathematical framework and the physic...

LES simulations at Re = 1 × 10⁵ and wind tunnel experiments at Re = 5 × 10⁵ were conducted to investigate the beneficial effect of an active flow control (AFC) technique on the aerodynamic performance of a simplified truck geometry. The paper involves the investigation of a synthetic jet actuator characterized by periodic blowing and suction that d...

The computational technology jointly developed by the N. N. Semenov Federal Research Center for Chemical Physics (ICP) and AVL LIST GmbH is used for simulating the operation process in a Rotating Detonation Engine (RDE) with an annular combustor and separate supply of fuel (natural gas (NG)) and oxidizer (gaseous oxygen). Particular attention is pa...

In this paper, we propose a method of three-dimensional direct numerical simulation of turbulent flame propagation in gas-reacting mixtures under stationary, homogeneous, and isotropic turbulence conditions. This method is based on the detailed kinetic mechanism of combustion of a multicomponent mixture, does not contain any adjustable parameters,...

The flow past a generic ship model is investigated numerically using well-resolved large eddy simulations at Re = 8 × 10 4 . The geometric configuration at the rear of the model is analogous to a double backward facing step, and it permits the occurrence of bi-stable flow states on each step; with an asymmetrical flow topology being observed in eac...

In contrast to the well-established “standard” log-law wall function, the analytical wall function (AWF) as an advanced modelling approach has not been extensively used in the industrial computational fluid dynamics (CFD) applications. As the model was originally developed aiming at computations on relatively coarse meshes, potential stability issu...

In this paper, we propose a cell-centered finite volume method for advective and normal flows on polyhedron meshes which is second-order accurate in space and time for smooth solutions. In order to overcome a time restriction caused by CFL condition, an implicit time discretization of inflow fluxes and an explicit time discretization of outflow flu...

The flow past a simplified frigate shape model which is analogous to a finite-width double backward facing step is investigated numerically using well-resolved large eddy simulations at Re≃8×10 ⁴ . The geometric configuration of this model permits the occurrence of bi-stable flow states, with an asymmetrical flow topology being observed in the late...

Recent experimental investigations by McArthur et al. (J. Fluids Struct. 66, 293–314, 2016) in the wake of a simplified heavy vehicle or commonly known as the ground transportation system (GTS) model has shown that the flow topology is invariant over a large range of Reynolds numbers [2.7 × 10⁴ − 2 × 10⁶]. Numerical simulations are performed to inv...

A tornado is a destructive rotating column of air extending from a cloud to the ground. It may kill people and damage property. Also there are possibilities of derailment of trains. Some train-turnover accidents are suspected to have been caused by tornadoes in Japan. For instance, a train of the JR Uestu line was overturned by a gust in 2005. Acco...

The near-wake flow topology of a ground transportation system (GTS) is investigated using partially-averaged Navier–Stokes (PANS) simulations at
. Recent numerical investigations for the GTS model using large eddy simulations (LES) showed an anti-symmetric flow topology (flow state II) in the vertical midplane compared to that observed in previous...

The bridging HRL (hybrid RANS/LES) method is being increasingly used to solve complex and high-Reynolds number industrial flows. The increase in popularity is
equally due to the conceptual simplicity and the potential ability to affect cut-off at an optimal length scale depending upon the problem on hand. In the bridging type
of HRL methods, the ra...

The near-wake flow topology of a ground transportation system (GTS) is investigated using partially-averaged
Navier–Stokes (PANS) simulations at Re ¼ 2:7� 104. Recent numerical investigations for the GTS model using
large eddy simulations (LES) showed an anti-symmetric flow topology (flow state II) in the vertical midplane
compared to that observed...

The prediction of flow past a generic ship has been performed using partially-averaged Navier–Stokes (PANS) turbulence model. The Reynolds number based on the width of the ship is 8×10⁴. A detailed comparison with resolved large-eddy simulation (LES) solution and available experimental data is made for a better understanding of the capability of PA...

LES simulations at Re = 1 × 10^5 and wind tunnel experiments at Re = 5 × 10^5 were conducted to investigate the beneficial effect of an active flow control (AFC) technique on the aerodynamic performance of a simplified truck geometry. The paper involves the investigation of a synthetic jet actuator characterized by periodic blowing and suction that...

Recent experiments [1, 2] in the wake of a simplified heavy vehicle (also know as a ground transportation system (GTS)) have shown that the flow topology remains invariant over a large range of Reynolds numbers [3.8 × 10 4 − 2.8 × 10 6 ]. This allows numerical techniques such as large eddy simulations (LES) to accurately predict the flow topology a...

Main drawback of the Reynolds-averaged Navier-Stokes (RANS) predictions of heat transfer at elevated Prandtl numbers is lack of accuracy, accompanied with increased mesh sensitivity. Even in conjunction with an accurate near-wall turbulence modeling, majority of the wall heat transfer models (based on the so-called P functions) fails to capture hea...

Computational Fluid Dynamics (CFD) is regularly used today to analyze and solve the problems in a wide range of different industries. CFD tools are especially well-established in the automotive industry. Countless calculations are routinely performed within certain level of accuracy specified by numerical and physical modelling limitations. Applied...

This work presents an application of the partially averaged Navier–Stokes (PANS) equations for an external vehicle flow. In particular, the flow around a generic truck cabin is simulated. The PANS method is first validated against experiments and resolved large
eddy simulation (LES) on two static cases. As a consequence, PANS is used to study the
e...

Aerodynamic properties of a BMW car model taking over a truck model are studied computationally by applying the scale-resolving PANS (Partially-averaged Navier-Stokes) approach. Both vehicles represent down-scaled (1:2.5), geometrically-similar models of realistic vehicle configurations for which on-road measurements have been performed by Schrefl...

Nowadays it is commonly accepted to report on convections schemes in the case of Large Eddy Simulations. However, this is still not mandatory for the hybrid Reynolds-Averaged Navier-Stokes (RANS)—LES calculations. Therefore, this paper intends to show that the effects of convection scheme is equally important for hybrid RANS-LES calculations as wel...

Recent experimental investigations in the wake of an idealised car model – the Ahmed body showed the existence of two stable wake states: flow state I, where the flow is fully separated over the back slant of the Ahmed body, and flow state II, where the flow initially separates and then reattaches further along the back slant. The existence of the...

A numerical method for solving diffusion problems on polyhedral meshes is presented. It is based on a finite volume approximation with the degrees of freedom located in the centers of computational cells. A numerical gradient is defined by a least-squares minimization for each cell, where we suggest a restricted form in the case of discontinuous di...

This paper presents a drag reduction study using active flow control (AFC) on a generic bluff body. The model consists of a simplified truck cabin, characterized by sharp edge separation on top and bottom edges and pressure induced separation on the two other rounded vertical front corners. The pressure induced separation reproduces the flow detach...

This paper presents a drag reduction study using active flow control (AFC) on a generic bluff body. The model consists of a simplified truck cabin, characterized by sharp edge separation on top and bottom edges and pressure induced separation on the two other rounded vertical front corners. The pressure induced separation reproduces the flow detach...

Two unsteady numerical techniques, Partially-Averaged Navier Stokes (PANS) and Large Eddy Simulation (LES), are used to predict the flow in a tube bundle. The results were compared with the existing experimental data. Both methods predicted the flow in a relatively good agreement with the experimental data although the PANS simulation used only fif...

This work presents an application of the Partially-Averaged Navier-Stokes equations for an external vehicle flow. In particular, the flow around a generic truck cabin is simulated. The PANS method is first validated against experiments and resolved LES on two static cases. As a consequence, PANS is used to study the effect of an active flow control...

An inflow-based gradient is proposed to solve a propagation in a normal direction with a cell-centered finite volume method. The proposed discretization of the magnitude of gradient is an extension of Rouy–Tourin scheme (SIAM J Numer Anal 29:867–884, 1992) and Osher–Sethian scheme (J Comput Phys 79:12–49, 1988) in two cases; the first is that the p...

In this paper, a semi-implicit method is proposed to solve a propagation in a normal direction with a cell-centered finite volume method. An inflow-based gradient is used to discretize the magnitude of the gradient and it brings the second order upwind difference in an evenly spaced one dimensional domain. In three dimensional domain, we numericall...

RANS computations of heat transfer involving wall bounded flows at elevated Prandtl numbers typically suffer from a lack of accuracy and/or increased mesh dependency. This can be often attributed to an improper near-wall turbulence modeling and the deficiency of the wall heat transfer models (based on the so called P-functions) that do not properly...

The entry of a shock wave from air into water containing reactive gas (stoichiometric acetylene–oxygen mixture) bubbles uniformly distributed over the volume of the liquid has been numerically investigated using equations describing two-phase compressible viscous reactive flow. It has been demonstrated that a steady-state supersonic self-sustaining...

Large Eddy Simulations (LES) are conducted to study the actuated flow field around a bluff body. The model is a simplified section of a truck. The aim of the work is to model the separation of the flow acting at the front rounded corners, the so called A-pillars, and to minimize the separation of the flow by means of Zero Net Mass Flux synthetic je...

This work presents the achievement in drag reduction by use of Active Flow Control (AFC) on a generic bluff body. The model consists of a simplified truck cabin, characterized by sharp edge separation on top and bottom edges and pressure induced separation on the rounded vertical front corner. The pressure induced separation reproduces the flow sep...

The complete understanding of jet primary breakup process is still not at our disposal, owing to the extremely complex interplay of different effects which are taking place during jet disintegration. It is widely accepted that the main influencing phenomena are: turbulence, aerodynamic forces, surface tension and cavitation, where some of them are...

Recent developments in the engine heat transfer modeling tend to improve existing wall heat transfer models (temperature wall functions) which mostly rely on the standard or low-Re variants of k-ε turbulence model. Presently applied mesh resolutions already allow for first near-wall computational cells reaching the buffer or locally even viscous/co...

Partially-Averaged Navier-Stokes Simulations (PANS) were made of flow around a generic vehicle influenced by side wind at four different yaw angles to investigate the prediction capabilities of PANS. Comparisons with results of LES show clear advantages of PANS in predicting pressure-induced separation resulting in the trailing vortices aligned wit...

Thepresentwork is concernedwiththe computational investigation of aerodynamic properties of the so-called ‘DrivAer’ car model representing a ‘generic realistic car configuration’ created by ‘merging’ the original geometries of two medium sized cars from the Audi A4 and the BMW 3 series, Heft et al. [7]. Three down-scaled (1:2.5) configurations diff...

The paper reports a study about the prediction of flows around simplified vehicles using Partially-Averaged Navier–Stokes (PANS). Numerical simulations are performed for two simplified vehicles: a slanted-back Ahmed body at Re = 30,000 and a squared-back Ahmed body at Re = 300,000. A comparison of the resolved and modeled physical flow scales is ma...

The present work improves performance of the wall heat transfer model of Han and Reitz employing advanced turbulence modeling and formulating a compressible wall function in the framework of hybrid wall treatment. Some ambiguities related to the originally published model of Han and Reitz are discussed in order to provide a basis for the present mo...

The aim of this paper is to present the adjoint equations for shape optimization derived from steady incompressible Navier-Stokes (N-S) equations and an objective functional. These adjoint Navier-Stokes equations have a similar form as the N-S equations, while the source terms and the boundary conditions depend on the chosen objective. Additionally...

The paper discusses the PANS model in the framework of engineering applications of bluff body flows. Comparisons with the resolving LES technique and URANS of a three dimensional bluff body flow are made for a better understanding of the behavior of PANS model in these flows. Several implementation issues of PANS such as fk variable in space and ti...

The Partially-Averaged Navier–Stokes (PANS) method is intended to provide the optimum fidelity on any given numerical grid while varying seamlessly between the Reynolds-Averaged Navier–Stokes (RANS) model and direct numerical simulation (DNS). This method belongs to so called bridging or seamless methods. The PANS method has been more often used in...

The present work is concerned with the application of the PANS-ζ -f (Partially-Averaged Navier-Stokes) variable resolutionmodel by Basara et al. (AIAA J 49:2627–2636, 2011), formulated in conjunction with the universal wall treatment, to the process of generation and destruction of a tumbling vortex in a squarepiston compression machine (investigat...