Implicit Large Eddy Simulation Research Articles

Generation and annihilation of three dimensional magnetic nulls in extrapolated solar coronal magnetic field: Data-based Implicit Large Eddy Simulation

Abstract Three-dimensional (3D) magnetic nulls are the points where magnetic field vanishes and are preferential sites for magnetic reconnection: a fundamental process which converts magnetic energy into kinetic energy, heat, and energy of non-thermal particles along with a rearrangement of magnetic field lines. Reconnection is ubiquitous in nature and plays a major role in various magnetically confined laboratory and space/astrophysical plasmas. In the solar corona, the reconnection manifests as coronal transients including solar flares, coronal mass ejections and coronal jets---often associated with 3D nulls. The nulls are generally found to be collocated with complex active regions on the solar photosphere and merits further attention, particularly in terms of their generation. A recent idealized magnetohydrodynamics simulation initiated with an analytically constructed preexisting proper radial null has identified magnetic reconnection to be responsible for spontaneous generation of these 3D nulls. It is then imperative to further explore the plausibility of spontaneous generation of nulls in naturally occurring plasmas, identify the mechanism and verify the outcome vis-\`a-vis observations. An apt test bed for such an initiative is the solar atmosphere, as abundant space and ground-based observations are available. In the above backdrop, the paper attempts to investigate 3D null generation by carrying out a data-based simulation of a C6.6 class flare associated with the photospheric active region NOAA $11977$. The simulation confirms spontaneous pairwise generation of 3D nulls with magnetic reconnections as the underlying cause. Importantly, magnetic field lines associated with the spontaneously generated nulls are found to trace observed chromospheric bright points---highlighting their observational relevance. Overall, such spontaneous generation and annihilation of nulls through magnetic reconnections opens up a new avenue for solar coronal and chromospheric heating.

Characteristics of Laminar Separation Bubble With Varying Leading-Edge Shapes and Deflections of the Trailing-Edge Flap

Abstract A series of implicit large eddy simulations (ILES) is carried out to examine the characteristics of a leading edge (LE) separation bubble. The test case comprises a flat plate with an elliptic leading edge (ELE), which is equipped with a trailing edge flap. Simulations are carried out (a) at three different flap angles (20 deg, 30 deg, 90 deg) and (b) using two different geometries of ELE where the ratio of the semimajor to semiminor axis is set to either 2:1 or 4:1. The flap is modeled using the immersed boundary method, which is computationally economical as it avoids regenerating the grid for varying flap angles. The results show that (a) the flow separates at lower flap deflection angles with a decrease in the aspect ratio of the ELE from 4:1 to 2:1 (b) an increase in the flap angle promotes separation at the LE due to an increase in the blockage in the bottom passage and a subsequent increase in the flow incidence at the leading edge. Simulations are also carried out using the γ−Reθ transition model and comparisons are drawn against ILES and experiments. Although the qualitative trends predicted using both ILES and Reynolds-Averaged Navier–Stokes (RANS) agree with the experiments, both approaches predict relatively shorter separation bubbles. This is attributed to the excess flow blockage in experiments due to the support plates, which are not modeled in the simulations. Nevertheless, the results demonstrate the superior accuracy of ILES over the RANS model.

On the extension of a Riemann solver for RANS simulations

Purpose Reynolds-averaged Navier–Stokes (RANS) models often perform poorly in shock/turbulence interaction regions, resulting in excessive wall heat load and incorrect representation of the separation length in shockwave/turbulent boundary layer interactions. The authors suggest that this can be traced back to inadequate numerical treatment of the inviscid fluxes. The purpose of this study is an extension to the well-known Harten, Lax, van Leer, Einfeldt (HLLE) Riemann solver to overcome this issue. Design/methodology/approach It explicitly takes into account the broadening of waves due to the averaging procedure, which adds numerical dissipation and reduces excessive turbulence production across shocks. The scheme is derived based on the HLLE equations, and it is tested against three numerical experiments. Findings Sod’s shock tube case shows that the scheme succeeds in reducing turbulence amplification across shocks. A shock-free turbulent flat plate boundary layer indicates that smooth flow at moderate turbulence intensity is largely unaffected by the scheme. A shock/turbulent boundary layer interaction case with higher turbulence intensity shows that the added numerical dissipation can, however, impair the wall heat flux distribution. Originality/value The proposed scheme is motivated by implicit large eddy simulations that use numerical dissipation as subgrid-scale model. Introducing physical aspects of turbulence into the numerical treatment for RANS simulations is a novel approach.

Effect of Transition on Self-Sustained Shock Oscillations in Highly Loaded Transonic Rotors

Recent trends in numerical studies suggest the possible need for scale-resolving simulations for resolving shock oscillations on transonic compressors, the sources of which are unclear. The effect of promoting transition on the suction side upstream of self-sustained shock oscillations from a laminar shock/boundary-layer interaction (altitude conditions) in transonic compressors is studied using implicit large-eddy simulation, as well as experiments in a transonic cascade. The experiment is performed at conditions leading to different shock structures, and the shock behavior is captured with high-speed schlieren imaging. The Rolls-Royce HYDRA in-house code is employed for the numerical simulations. Trends in the change of oscillation behavior are discussed. The work addresses the fundamentally different behavior between an idealized quasi-2D LES case and an experimental cascade. This suggests that a simplification of the shock oscillation problem to a more canonical form is needed in order to investigate the oscillation mechanism itself experimentally and validate the CFD of the mechanism before returning to more complex cases. The reader is referred to youtu.be/CNRz7IYl1Pk for a condensed summary of the work with flow visualization.

Regulating turbulent separation by surface microstructures on a blunt plate

Microstructured surfaces can induce secondary flow and regulate flow structures of the turbulent separation flow. However, the mechanism governing the relationship between the microstructure size and the characteristic flow size remains unclear. In this study, the separated flow over a blunt flat plate with surface microstructures is studied using time-resolved particle image velocimetry experiments and implicit large-eddy simulations for the plate-thickness-based Reynolds number from 5.08×103 to 1.31×104. The ratio of the height of microstructures to the plate thickness (h/d) ranges from 0.01 to 0.1. Combining experimental and numerical results, the relationships between the separation bubble size and the microstructure size under different Reynolds numbers exhibit similarity when normalized by the separation bubble size of the smooth plate. The dimensionless separation bubble size decreases when the microstructure height increases and large microstructures (h/d = 0.1) exhibit good performance on reducing the flow separation. Near the leading edge, the distortion of two-dimensional vortices and the generation of three-dimensional hairpin vortices are promoted by the first several rows of large microstructures. Additionally, in the main separation region, secondary positive spanwise vortices emerge from large microstructures. Subsequently, the secondary vortices lift up and evolve into streamwise vortices. The characteristic scale of secondary vortices is represented by a significant peak in the spectra of spanwise wavenumbers, which is of the same magnitude as the height of large microstructures. Furthermore, increasing the microstructure height weakens the streamwise correlation of the flow, and the characteristic scale of the correlation is comparable to the height of large microstructures.

Exploration of High-Frequency Actuation on Gust Response Using Large Eddy Simulation

Abstract Mitigation of gust-induced separation and aerodynamic loads using a high-frequency blowing/suction slot is demonstrated using high-order implicit large eddy simulation (LES). This approach was previously shown to be effective at alleviating dynamic stall on pitching wings. A NACA0012 wing section operating at a transitional chord-based Reynolds number of Rec=500,000, subsonic freestream Mach number of M∞=0.1, and angles of attack of α = 4 deg and 12 deg is subjected to discrete 1-cos transverse gusts. Gust-induced stall is demonstrated and then active flow control (AFC) is applied to cases vulnerable to gust-induced stall. The flow control strategy is shown to be effective at stall suppression during gust encounter, thereby providing partial alleviation of gust induced loads. This approach is most effective at attenuating pitching moment increment.

Flow–acoustic resonance mechanism in tandem deep cavities coupled with acoustic eigenmodes in turbulent shear layers

This study presents the interplay of flow and acoustics within tandem deep cavities, focusing on the resonance mechanism occurring between turbulent shear layers and acoustic eigenmodes. The arrangement inside the tandem deep cavities includes both close and remote configurations. A combined fully coupled and decoupled aeroacoustic simulation strategy was devised. Employing an advanced high-order spectral/hp element method in conjunction with implicit large eddy simulation, the nonlinear compressible Navier–Stokes equations were solved to acquire internal flow–acoustic resonant field. In parallel, the linearized Navier–Stokes equations were tackled to determine coherent shear layer perturbations with external acoustic forcing. Based on acoustic measurements, the mainstream Reynolds number approaches approximately $R{e_{in}} = {O}({10^5})$ , where we identified the presence of frequency lock-in and a resonance range. Aeroacoustic noise sources were examined by implementing spectral proper orthogonal decomposition to decompose the pressure fields into hydrodynamic and acoustic components. As feedback intensified, the flow characteristics by the acoustic forcing effect and the flow-interactive effect were categorized according to the development of concurrent turbulent shear layers. Subsequently, the alternating and synchronous behaviours of concurrent shear layers resonated with the out-of-phase and in-phase acoustic eigenmodes were identified, and the corresponding large-scale counter-rotating vortex pairs and co-rotating vortex structures at the cavity entrances were extracted. The acoustic power generated by the Coriolis force was calculated using Howe's vortex-sound analogy, and the aeroacoustic energy transfer mechanism between large-scale shear layer vortices with acoustic eigenmodes was further explored. Finally, a linear response of coherent perturbations of the concurrent shear layers by external acoustic forcing was established. The amplification of flow in the streamwise direction toward the main duct led to the formation of coherent vortex structures, accompanied by separation bubbles into the main duct.

Prediction of the Influence of the Inlet End-Wall Boundary Layer on the Secondary Flow of a Low Pressure Turbine Airfoil Using RANS and Large-Eddy Simulations

Abstract This paper analyzes the effect of the inlet end-wall boundary layer on the secondary flow of a low pressure turbine airfoil cascade at Reynolds number 2 × 105 using RANS and implicit large-eddy simulations (LES). The results are compared against experimental data obtained at two low-speed linear cascade facilities, one located at the Whittle Laboratory of the University of Cambridge and the other at the Polytechnic University of Madrid. The RANS turbulence model is the k−ω−γ−Reθt and no sub-grid scale model has been used in the LES. An unstructured mesh of hexahedra and prisms is used, with high order elements used in the boundary layer region to better describe the airfoil shape in the LES. Two inlet end-wall boundary layers that produce different secondary flow patterns are analyzed: a laminar thin velocity profile and a turbulent thick velocity profile with several inlet turbulent intensities. The agreement between LES numerical predictions and experimental measurements of the position and intensity of the secondary vortices is very good for both cases. RANS simulations are much cheaper in terms of computational cost and reasonably predict most of the flow features, except when the inlet turbulence is low and turbulent transition prediction becomes critical. The effect of the inlet velocity profiles and inlet turbulence on the secondary flow structure is quite pronounced. The velocity profile thickness determines the spanwise penetration of the passage vortex, and different inlet turbulence intensities modify its mixing. Higher inlet turbulence intensities lead to a decrease of the secondary losses due to the passage vortex and an increase of end-wall losses.

Joint-mode diffusion analysis of discontinuous Galerkin methods: Towards superior dissipation estimates for nonlinear problems and implicit LES

We present a new linear eigensolution analysis technique that provides superior estimates of dissipation distribution in wavenumber space for the discontinuous Galerkin (DG) method. The technique builds upon traditional dispersion-diffusion analyses that have been applied to spectral/hp element methods, but in particular is an improvement upon the non-modal eigenanalysis approach proposed by Fernandez et al. in [1]. The present technique takes into account the indirect effects that dispersion may have on dissipation, as recently discussed by Moura et al. in [2], in order to better represent dissipation itself. Also, a concept often used with dynamic mode decomposition (DMD) techniques is invoked to weight the relative contribution of the multiple diffusion curves that stem from temporal eigenanalysis. This allows for obtaining a single dissipation profile in wavenumber space, so that the proposed technique is named joint-mode analysis. Although the non-modal approach also provides a single diffusion curve, the joint-mode dissipation curve is shown to correlate significantly better with the energy spectrum of Burgers' turbulence at large and intermediate scales, which is particularly relevant for implicit large-eddy simulation (LES). The proposed technique is readily extensible to other spectral/hp element methods.

Modeling of the influence of local heat sources on a light gas stratification formation and erosion in a large-scale experimental facility using eddy resolving numerical approach

The main objective of this work is to evaluate the results of application of Implicit Large Eddy Simulation (ILES) turbulence modeling approach to simulate the complex hydrogen safety problem. The paper presents the results of numerical simulation of the OECD/NEA HYMERES (HYdrogen Mitigation Experiments for Reactor Safety) HP2 series tests in the PANDA facility, aimed at studying the thermal effect of passive autocatalytic recombiner (PAR) operation on mixing the containment atmosphere, using CABARET-SC1 code. The code is based on the eddy resolving CABARET technique, which allows implicit modeling of the subgrid turbulence scales without using tuning parameters (ILES approximation). The natural convection flow inside the PAR model was calculated explicitly using a simplified model of the heating section and the housing. Good agreement of calculated transient with experimental data was obtained, which indicates the effectiveness of such approach.

Implicit large-eddy simulation of an over-expanded screeching rectangular jet

Implicit large-eddy simulation of an over-expanded screeching rectangular jet is performed with a seventh-order finite difference scheme. Good agreement is found between the predicted flow- and acoustic fields with the experimental observations. Fourier decomposition, phase-averaging analysis and Spectral Proper Orthogonal Decomposition (SPOD) are used to investigate the origin of the screech, the shock leakage during the shear-layer flapping, and the distinguishing fluctuating characteristics in the minor- and major-axis plane of the rectangular jet. It finds that the screech is radiated from the end of the forth shock cell, where the interaction of the shock waves with the shear layer causes periodic leakages of shock-wave tips in the minor-axis plane, resulting in the generation of intense acoustic waves in the surrounding air. An obvious flapping mode at the same frequency of the screech is captured in the minor-axis plane and dominates the dynamic motions of the rectangular jet. The SPOD modes of pressure and velocity fluctuations at the screech frequency help to reveal the relationship between the screech generation and the coherent structures.

Calibrating sub-grid scale models for high-order wall-modeled large eddy simulation

AbstractHigh-order methods have demonstrated orders of magnitude reduction in computational cost for large eddy simulation (LES) over low-order methods in the past decade. Most such simulations are wall-resolved implicit LES (ILES) without an explicit sub-grid scale (SGS) model. The use of high-order ILES for severely under-resolved LES such as wall-modeled LES (WMLES) often runs into robustness and accuracy issues due to the low dissipation embedded in these methods. In the present study, we investigate the performance of several popular SGS models, the static Smagorinsky model, the wall-adapting local eddy-viscosity (WALE) model and the Vreman model, to improve the robustness and accuracy of under-resolved LES using high-order methods. The models are implemented in the high-order unstructured grid LES solver called hpMusic based on the discontinuous flux reconstruction method. The length scales in these SGS models are calibrated using the direct numerical simulation (DNS) database for the turbulent channel flow problem. The Vreman model has been found to produce the most accurate and consistent results with a proper choice of the length scale for WMLES.

Thermal and fluid aspects of dual piezoelectric jet pump of double chambers

The rapid development of electronics has led to a significant reduction in the size of electronic devices, while increasing their power consumption. This has resulted in the need for small-scale thermal management solutions. Piezoelectric pump is one of the efficient devices for local thermal management. This paper presents a novel configuration of a piezoelectric pump, which separates the pump chamber with a rigid wall to create two independent pulsating flows. This configuration aims to reduce eddies within each chamber. Furthermore, the proposed design incorporates two pairs of open-sided channels to guide the pulsating flow towards the hot target. The electrostatics physic of the piezoelectric patches along with energy and momentum equations in three dimensions are manipulating mathematically and solved numerically using the finite element method (FEM) and the Arbitrary Lagrangian-Eulerian (ALE) technique. The implicit Large Eddy Simulation (iLES) turbulence model is adopted for this purpose. Several parameters, including frequency, voltage, and the radius of the piezoelectric patch are investigated to better understanding their influence on both the zero-net volumetric flow rate and the heat transfer process. The findings indicate that by separating the pump chamber, it becomes feasible to obtain a 3D solution with the iLES using a reasonable mesh size. Nusselt number increases with all the examined parameters, where it enhances by 42.48 % at V = 100 Volt when the pump is switched on compared to natural convection mode. The peak-peak volumetric flowrates rises by 50 % and 350 % when the applied voltage is raised from 50 to 100 Volts and the frequency is raised from 20 to 50.50 kHz, respectively.

Numerical investigation of cavitation vortex dynamics in different cavitation patterns coupled implicit large eddy simulation and boundary data immersion method

The objective of this paper is to investigate the flow characteristics of different cavitation flow patterns around a NACA (National Advisory Committee for Aeronautics) 66 hydrofoil by applying the BDIM (boundary data immersion method) and ILES (implicit large eddy simulation) with an artificial code. Meanwhile, an artificial compressibility method is also employed to consider the effects of compressibility on cavitating flow. The results present that the numerical method can effectively capture different cavitation patterns, which agrees well with the previous experimental data. Subsequently, the detailed analysis of vortex structures and dynamics for the non-cavitation (σ = 3.0), sheet cavitation (σ = 2.0), and cloud cavitation (σ = 1.6) cases with the Liutex method and the vortex enstrophy transport equation have been investigated. When cavitation occurs, the degree of turbulence and the enstrophy in the flow field have been enhanced, due to the disturbance of the velocity field. For sheet cavitation, complex vortex structures appear in the attached cavity region with high-intensity enstrophy causing by the highly intense velocity and density gradient. As the cavitation pattern transits from the sheet cavitation to the cloud cavitation, more complex vortex structures can be observed in the cavitation region. Furthermore, the value and the fluctuation amplitude of enstrophy intensity increase significantly under the effect of reentrant jet. Analysis of the enstrophy transport equation indicates that the vortex stretching term and dilatation term for cloud cavitation increase relatively significantly with the movement of the reentrant flow and are highly dependent on the cavitation evolution. In addition, the region affected by the baroclinic torque also increases.

Composite control of airfoil broadband noise based on the combination of porous material and serrated trailing edges

Improving the noise reduction capability of airfoil broadband noise through serrated trailing edge design is a challenging task. To address this, we propose a novel porous-serrated trailing edge design where the gaps between the serrations are filled with porous media. Implicit large eddy simulations were conducted at Mach number Ma=0.1631 and Reynolds number Re=96 000 under a zero incidence angle. In addition to straight trailing edges and conventional serrated trailing edges, cutting-type porous-serrated (CPS) and insert-type porous-serrated (IPS) trailing edges with different porosities were designed. The flow in the porous media is described by Darcy's law, which is related to the pressure and velocity. The results indicate that the CPS trailing edges offer limited noise reduction compared to conventional serrated trailing edges, while IPS trailing edges achieve a significant noise reduction of approximately 5.21 dB. However, the drag force increases by 8.0% in the IPS case with maximum noise reduction. The composite control mainly affects flow structures near the trailing edges, especially inducing the flow penetration across the porous surface. To investigate the noise reduction mechanism, dynamic mode decomposition was conducted to show that both the CPS and IPS designs promote energy transferring significantly from the energetic mode to the modes at other frequencies, which would partly explain the difference in the noise reduction performance to some extent. Furthermore, the analysis of the wall pressure fluctuations reveals that the reduced convection velocity on the porous surface and enhanced destructive interference between the porous and the solid surfaces in IPS cases could be identified as the key factors contributing to lower noise radiation efficiency.

Harmonic Turbulent Stress Budgets in Forced Transonic Flow over a Bump

The transonic flow over a bump is studied using implicit large-eddy simulations. To replicate rotor/stator interactions occurring in turbomachinery, harmonic forcing of the backpressure is imposed at the outlet. Various perturbation frequencies are prescribed and encompass different regimes, from a fully locked configuration to a decoupling between the unperturbed and forced flows. The mean solution is, however, found to be independent of the perturbation. In a triple-decomposition framework, the coherent component of the flow is extracted by phase averaging. Organized structures of streamwise velocity and turbulence kinetic energy are highlighted. Whereas these structures are of similar shapes beneath the shock system, their extent in the downstream boundary layer is controlled by the frequency of the perturbation. The mean and harmonic turbulent stress budgets are presented. A typical three-peak distribution of mean turbulent diffusion is reported, which is also found to appear for coherent turbulent diffusion. Harmonic production arises mainly from the mean shear and its modulation.

A method for examining ensemble averaging forms during the transition to turbulence in HED systems for application to RANS models

This paper discusses a strategy to initialize a two-dimensional (2D) Reynolds-averaged Navier–Stokes model [LANL's Besnard–Harlow–Rauenzahn (BHR) model] in order to describe an unsteady transitional Richtmyer–Meshkov (RM)-induced flow observed in on-going high-energy-density ensemble experiments performed on the OMEGA-EP facility. The experiments consist of a nominal single-mode perturbation (initial amplitude a0≈10 and wavelength λ=100 μm) with target-to-target variations in the surface roughness subjected to the RM instability with delayed Rayleigh–Taylor in a heavy-to-light configuration. Our strategy leverages high-resolution three-dimensional (3D) implicit large eddy simulations (ILES) simulations to initialize BHR-relevant parameters and subsequently validate the 2D BHR results against the 3D ILES simulations. A suite of five 3D ILES simulations corresponding to five experimental target profiles is undertaken to generate an ensemble dataset. Using ensemble averages from the 3D simulations to initialize the turbulent kinetic energy in the BHR model (K0) demonstrates the ability of the model to predict the time evolution of the interface as well as the density-specific-volume covariance, b. To quantify the sensitivity of the BHR results to the choice of K0 and the initial turbulent length scale, S0, we execute a parameter sweep spanning four orders of magnitude for both S0 and K0, generating a parameter space consisting of 26 simulations. The Pearson's correlation coefficient is used as a measure of discrepancy between the 2D BHR and 3D ILES simulations and reveals that the ranges 8≲S0≲20 μm and 109≲K0≲1010 cm2/s2 produce predictions that agree best with the 3D ILES results.

Explicit and implicit large eddy simulations of variable-density low-speed flows

The application of the Non-oscillatory Forward-in-Time (NFT) class of solvers to facilitate conventional explicit Large Eddy Simulations (LES) and implicit LES (ILES) of low-speed turbulent flow encompassing substantial local density variations is explored. Schemes solving two different sets of Low Mach Number (LMN) equations are proposed with the aim of capturing variable-density effects arising from either a non-isothermal distribution in single-species flow or compositional variation occurring in a binary-species mixing under isothermal conditions. Both schemes employ the semi-implicit NFT integrators based on the Multidimensional Positive Definite Advection Transport Algorithm and a non-symmetric Krylov subspace solver for the variable-coefficient Poisson problems arising from different treatments applied to the non-zero velocity divergence term in the two sets of the LMN equations. The developments are successfully validated using three diverse test cases, differentially heated cavity flow, non-isothermal free-jets, and a helium plume. The reported simulations show that both the dynamic Smagorinsky model in LES and ILES subgrid-scale treatments yield similar accuracy in capturing turbulent effects for the considered flows.

Flow fields around asymmetrical micro vortex generators in supersonic flow

Motivated by the favorable effects of asymmetrical vortical structures on shock-wave boundary layer interactions, we performed implicit large-eddy simulations to analyze the ability of micro mechanical vortex generators (VGs) to generate such structures. For this purpose, we studied modified VG geometries, by skewing and varying the orientation of a microramp and introducing pairs of unevenly sized ramped-vanes. The modified VGs allow to study the effectiveness of these devices when operating in off-design conditions. The flow physics of all devices were investigated in a supersonic crossflow at Mach 2.5 and a momentum-thickness Reynolds number of 7000. The flow topology around each VG is very similar: the VG acts as an obstacle to the incoming flow and induces a complex system of shocks, recirculation regions, and vortical structures. We present a detailed study of the evolution of the dominant major counter-rotating vortex pair (CVP) to estimate the VGs' flow-control effectiveness. All modified configurations introduce asymmetry into the flow, yet to varying degree for different device types. The modifications made to the microramp have minimal impact on the boundary layer, while the uneven ramped-vane configurations have significant effect. Lateral spread of mechanical VG induced major CVP is not larger than the spanwise dimension of the VG. Consequently, the favorable effect of interactions between VGs arranged in arrays on flow-control effectiveness observed for air-jet VG arrays cannot be reproduced with mechanical VGs. Considering the large design offsets we introduced to the microramp and ramped-vane configurations, both device types are robust to off-design flight conditions.

Extended Hypothesis for Reynolds Stress Tensor and Turbulent Heat Flux Modeling Within a Novel K‐ε Model for Prediction of Crystal Growth from the Melt

AbstractThe major technique of manufacturing silicon monocrystals is Czochralski (Cz) method. To obtain high‐quality crystals, it is necessary to control the melt flow that is turbulent. The most cost‐effective approach for modeling turbulence nowadays is RANS (Reynolds Averaged Navier‐Stokes) that allows for providing steady axisymmetric computations using reasonable grids. However, conventional eddy‐viscosity RANS models usually fail to predict spatial details of turbulence characteristics of the melt flow. To overcome the limitations of the eddy‐viscosity approach the Stress Tensor Reconstruction (STR) approach is developed that is aimed at the reproduction of anisotropy of the Reynolds stresses. The Generalized Gradient Diffusion Hypothesis (GGDH) in combination with the STR approach successfully takes into account the anisotropy of turbulent fluxes in a melt flow. Relying upon the STR/GGDH approach a novel RANS STR k‐ε model is developed. The model is validated using the ILES (Implicit Large Eddy Simulation) data of turbulent melt convection during Cz Si crystal growth, as well, as the experimental data of oxygen concentration in 100 and 200 mm diameter Cz crystals. The results are compared to the results obtained with the conventional low Reynolds number Chien k‐ε model extended by the buoyancy generation term.