Numerical simulation of rotating channel flow based on a modified DES model

2021 ◽  
pp. 2150193
Author(s):  
Peifeng Lin ◽  
Pu Wang ◽  
Yong Zhou ◽  
Xiaojun Li
Keyword(s):  
Channel Flow ◽  
Energy Transport ◽  
Turbulent Viscosity ◽  
Internal Flow ◽  
Additional Term ◽  
Detached Eddy Simulation ◽  
Turbulence Statistics ◽  
Eddy Simulation ◽  
New Type ◽  
Rotating Channel

A new type of nonlinear sub-grid scale (SGS) model is adopted based on the helicity analysis and is verified by predicting the internal flow in a rotating channel. A stress term that contains helicity constraint is introduced into the original SGS model to construct a nonlinear sub-grid model. This additional term representing the helicity constraint effect in the momentum equations is shown to give predictions that are in better agreement with the experimental data. In this paper, the Detached-Eddy Simulation (DES) and the nonlinear SGS model are used to further study the turbulence statistics of the rotating channel flow. Combining with the Reynolds stress transport equations and the turbulent kinetic energy transport equation, the change of turbulence statistics near the wall of the rotating channel is analyzed. The newly added term changes the turbulent viscosity near the wall, which changes the velocity gradient near the wall and further affects other turbulence statistics near the wall.

scholarly journals Large-Eddy Simulation of Internal Flow through Human Vocal Folds

2018 ◽  
Vol 180 ◽  
pp. 02054
Author(s):  
Martin Lasota ◽  
Petr Šidlof
Keyword(s):  
Large Eddy Simulation ◽  
Stokes Equations ◽  
Turbulent Viscosity ◽  
Internal Flow ◽  
Vocal Folds ◽  
Computational Domain ◽  
Subgrid Scale ◽  
Eddy Simulation ◽  
Scale Models ◽  
Large Eddy

The phonatory process occurs when air is expelled from the lungs through the glottis and the pressure drop causes flow-induced oscillations of the vocal folds. The flow fields created in phonation are highly unsteady and the coherent vortex structures are also generated. For accuracy it is essential to compute on humanlike computational domain and appropriate mathematical model. The work deals with numerical simulation of air flow within the space between plicae vocales and plicae vestibulares. In addition to the dynamic width of the rima glottidis, where the sound is generated, there are lateral ventriculus laryngis and sacculus laryngis included in the computational domain as well. The paper presents the results from OpenFOAM which are obtained with a large-eddy simulation using second-order finite volume discretization of incompressible Navier-Stokes equations. Large-eddy simulations with different subgrid scale models are executed on structured mesh. In these cases are used only the subgrid scale models which model turbulence via turbulent viscosity and Boussinesq approximation in subglottal and supraglottal area in larynx.

scholarly journals Numerical Investigation on Fluid Flow in a 90-Degree Curved Pipe with Large Curvature Ratio

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yan Wang ◽  
Quanlin Dong ◽  
Pengfei Wang
Keyword(s):  
Fluid Flow ◽  
Internal Flow ◽  
Fluid Flows ◽  
Detached Eddy Simulation ◽  
Number Range ◽  
Curvature Ratio ◽  
Large Curvature ◽  
Curved Pipe ◽  
Eddy Simulation ◽  
Curved Pipes

In order to understand the mechanism of fluid flows in curved pipes, a large number of theoretical and experimental researches have been performed. As a critical parameter of curved pipe, the curvature ratioδhas received much attention, but most of the values ofδare very small (δ<0.1) or relatively small (δ≤0.5). As a preliminary study and simulation this research studied the fluid flow in a 90-degree curved pipe of large curvature ratio. The Detached Eddy Simulation (DES) turbulence model was employed to investigate the fluid flows at the Reynolds number range from 5000 to 20000. After validation of the numerical strategy, the pressure and velocity distribution, pressure drop, fluid flow, and secondary flow along the curved pipe were illustrated. The results show that the fluid flow in a curved pipe with large curvature ratio seems to be unlike that in a curved pipe with small curvature ratio. Large curvature ratio makes the internal flow more complicated; thus, the flow patterns, the separation region, and the oscillatory flow are different.

Detached Eddy Simulation for Model Hydro Turbine

2006 ◽  
Author(s):  
Xiaojing Wu ◽  
Shuhong Liu ◽  
Yulin Wu
Keyword(s):  
Vortex Motion ◽  
Internal Flow ◽  
Simulation Method ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Complex Flow ◽  
Hydro Turbine ◽  
Eddy Simulation ◽  
Mesh Density ◽  
Flow Vortex

In this paper, detached eddy simulation method is applied to the numerical simulation for whole passage of a model hydro turbine. The method combines the strong points of Reynolds-averaged Navier-Stokes and Large eddy simulation. In this model, Spalart–Allmaras turbulent model is improved, which reduces to a RANS formulation near a solid surface and to a subgrid model away from the wall. The hexahedron type mesh is used to divide the model, which can decrease the mesh scale and computation cost. In this paper, a unsteady turbulent simulation is done for model hydro turbine with this viscous model. The internal flow, vortex motion and pressure fluctuation inside hydro turbine can be studied from the result, which are also compared with the experiment data. It can be seen that this method can describe the complex flow of the turbine well while the mesh density is not very high.

Analysis of a New Adjustable Mixer Base on Large Eddy Simulation

2012 ◽  
Vol 594-597 ◽  
pp. 2763-2769
Author(s):  
Xin Nie ◽  
Lin Xiang Ding ◽  
Bing Guo ◽  
Li Bo Chen ◽  
Hua Chen Pan
Keyword(s):  
Large Eddy Simulation ◽  
Colloidal Particles ◽  
Internal Flow ◽  
Mixing Efficiency ◽  
Eddy Simulation ◽  
Large Eddy ◽  
New Type ◽  
Speed Change ◽  
Large Velocity Gradient ◽  
Vortex Diffusion

Abstract. This paper presents a new type of adjustable mixing equipment, and the internal flow field of the adjustable mixer have been studied by using the model of LES(Large eddy simulation),and the pressure loss, the speed change and vortex scale have been studied. In conclusion, along with blades angle and number increases, the flow resistance increases violently, so the range of blade rotating angle should be controlled within 30 degrees. As the depth of the pipeline velocity is increasingly large, large velocity gradient is contributed to the collisions between the colloidal particles. In pre-mixed, the vortex effect of the pipeline highly enhances the vortex diffusion, and improves the mixing efficiency. The vortex strength will be reinforced and dimension will be reduced, with the vanes cutting the flow, which can help flocculation.

scholarly journals Hybrid Numerical Simulation of Jet Blast Distance of a Departing Aircraft

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xin He ◽  
Yaqing Chen ◽  
Yilong Ma ◽  
Dengfeng Hu ◽  
Haoran Gao
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Turbulence Model ◽  
Internal Flow ◽  
Aircraft Engine ◽  
Simulation Method ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Numerical Simulation Method

A hybrid numerical simulation method was established by combining the Spalart-Allmaras (SA) turbulence model and detached eddy simulation (DES). Numerical simulations were carried out to model cold and hot spray conditions of a nozzle without considering the internal flow of an engine to determine jet conditions. Analysis results show that the calculated hot spray results more in line with the reality. The jet effect of a typical aircraft engine was simulated numerically to determine the distance influenced by the jet blast from a departing aircraft engine.

Large Eddy Simulation of Rotating Channel Flows With and Without Heat Transfer

2000 ◽  
Author(s):  
Ning Meng ◽  
Richard H. Pletcher
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Channel Flow ◽  
Scale Effects ◽  
Scale Model ◽  
Finite Volume Scheme ◽  
Subgrid Scale ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Rotating Channel

Abstract Large eddy simulation of rotating channel flow with and without heat transfer is reported. The rotation axis is parallel to the spanwise direction of the parallel plate channel. An implicit finite-volume scheme was used to solve the preconditioned time-dependent filtered Navier-Stokes equations using a dynamic subgrid-scale model to account for the subgrid-scale effects. Comparisons are made with available results in the literature for isothermal rotating flows. The combined effects of rotation and heat transfer on the structure of turbulence channel flow is discussed.

scholarly journals Research and Application of Filtering Grid Scale in Detached Eddy Simulation Model

Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1252
Author(s):  
Liang Dong ◽  
Chao Guo ◽  
Ying Wang ◽  
Houlin Liu ◽  
Cui Dai
Keyword(s):  
Geometric Mean ◽  
Pressure Coefficient ◽  
Polar Angle ◽  
Internal Flow ◽  
Experimental Result ◽  
Detached Eddy Simulation ◽  
Quadratic Mean ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Flow Pressure

The existing definition method of filter grid scale in a Detached Eddy Simulation (DES) hybrid model is unreasonable, which will lead to the unreasonable trigger of a boundary layer large eddy simulation and reduce computational efficiency. In view of this problem, the filter grid scale is discussed in this paper. The 90° square curved elbow is selected as the research object. The effects of three grid definition methods: geometric mean (ΔGM), arithmetic mean (ΔAM) and quadratic mean (ΔQM) on the simulation results of the DES model are compared, and the velocity distribution of the flow cross section and the distribution of the flow pressure coefficient on the outer arc surface are compared with the experimental results of Taylor. The results show that the order of the three definition methods is ΔGM≤ΔAM≤ΔQM. Meanwhile, within 30° < polar angle(θ) < 75°, the results are closer to the experiment, and the development trends and numerical values of ΔAM and ΔQM are closer to the experiment in general. However, when θ > 60°, the value of ΔQM is slightly closer to the experimental result than ΔAM. ΔQM is more suitable for calculating the internal flow in a curved elbow than the other two methods.

HEAT TRANSFER ON PERIODICALLY DIMPLE-PROTRUSION PATTERNED WALLS IN TURBULENT CHANNEL FLOW

2014 ◽  
Vol 34 ◽  
pp. 1460372
Author(s):  
YU CHEN ◽  
T. CHEW ◽  
B. C. KHOO
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Channel Flow ◽  
Turbulent Channel Flow ◽  
Simulation Method ◽  
Detached Eddy Simulation ◽  
Test Channel ◽  
Eddy Simulation ◽  
Small Depth ◽  
Study Heat Transfer

In this study, heat transfer characteristics and flow structures over periodically dimple-protrusion patterned walls in a turbulent channel flow were systematically investigated using Detached Eddy Simulation method. The periodically patterned surface is applied to the bottom wall only in the test channel. It is found that larger depth/height induces higher friction factor and heat transfer. Furthermore, the highest Nusselt number is found to be located at the upstream portion of protrusion and the downstream portion of dimple. Additionally, the distributions of Nusselt number exhibit symmetrical features for the small depth/height configuration and asymmetric characteristics for the large depth/height configuration.

Wavelet-based adaptive delayed detached eddy simulations for wall-bounded compressible turbulent flows

2019 ◽  
Vol 873 ◽  
pp. 1116-1157 ◽  
Author(s):  
Xuan Ge ◽  
Oleg V. Vasilyev ◽  
M. Yousuff Hussaini
Keyword(s):  
Turbulent Flows ◽  
Channel Flow ◽  
Adaptive Mesh Refinement ◽  
Degrees Of Freedom ◽  
Mesh Refinement ◽  
Plane Channel ◽  
Adaptive Mesh ◽  
Adaptation Strategy ◽  
Detached Eddy Simulation ◽  
Eddy Simulation

A novel wavelet-based adaptive delayed detached eddy simulation (W-DDES) approach for simulations of wall-bounded compressible turbulent flows is proposed. The new approach utilizes anisotropic wavelet-based mesh refinement and its effectiveness is demonstrated for flow simulations using the Spalart–Allmaras DDES model. A variable wavelet thresholding strategy blending two distinct thresholds for the Reynolds-averaged Navier–Stokes (RANS) and large-eddy simulation (LES) regimes is used. A novel mesh adaptation on mean and fluctuating quantities with different wavelet threshold levels is proposed. The new strategy is more accurate and efficient compared to the adaptation on instantaneous quantities using a priori defined uniform thresholds. The effectiveness of the W-DDES method is demonstrated by comparing the results of the W-DDES simulations with results already available in the literature. Supersonic plane channel flow for two different configurations is tested as benchmark wall-bounded flows. Both the accuracy indicated by the threshold and efficiency in terms of degrees of freedom for the novel adaptation strategy are successfully gained compared with the wavelet-based adaptive LES method. Moreover, the newly proposed W-DDES resolves the typical log-layer match issue encountered in the conventional non-adaptive DDES method mainly due to the use of wavelet-based adaptive mesh refinement. The W-DDES capability for simulations of complex turbulent flows is validated by two other flow configurations – a subsonic channel flow with periodic hill constrictions and a supersonic flow over a compression ramp inducing the shock wave–turbulent boundary layer interaction. The current study serves as a crucial step towards construction of a unified wavelet-based adaptive hierarchical RANS/LES modelling framework, capable of performing simulations of varying fidelities from no-modelling direct numerical simulations to full-modelling RANS simulations.

Sign in / Sign up

Export Citation Format

Share Document