Comparison of Various Spatial Discretization Schemes in Numerical Simulation for Ship Airwakes

2014 ◽  
Vol 627 ◽  
pp. 63-68 ◽  
Author(s):  
Shao Hua He ◽  
Dong Yue Liu ◽  
Da Li Tan
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Cfd Simulation ◽  
Computational Cost ◽  
Second Order ◽  
Upwind Scheme ◽  
Spatial Discretization ◽  
Third Order ◽  
Quick Scheme ◽  
Discretization Schemes

For numerical simulation of ship airwake by CFD, based on the use of an unstructured grid, thek-εturbulence model and SIMPLE algorithm, the characteristic features of complex fluid flows eg recirculation zones and strong vortex fields in the aircarft operating region of a generic 3D frigate model was presented. The accuracy of the predication was checked by performing calculations on different grid sizes and comparing with wind-tunnel flow visualization data. A comparison of several typical spatial discretization schemes was performed.y+values were also tested. The general features of the flow predicted in this paper compare reasonably well with experimental data. However, CFD simulation produced a higher velocity in the vicinity of vortex zone when compared to experimental data. Obvious differences exist between results by first-order upwind scheme (power law scheme) and second-order upwind scheme (QUICK scheme, third-order MUSCL scheme). Second-order upwind scheme (QUICK scheme, third-order MUSCL scheme) are recommended for the CFD simulation of ship airwakes with a modest increase in computational cost.y+values from o (10) to o (1000) can all be accepted for the CFD simulation of ships (e.g., SFS1 ) with Reynolds number 108or more.

scholarly journals Assessment of Different CFD Modeling and Solving Approaches for a Supersonic Steam Ejector Simulation

Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 144
Author(s):  
Jingshu Xiao ◽  
Qiao Wu ◽  
Lizhou Chen ◽  
Weichang Ke ◽  
Cong Wu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Second Order ◽  
Back Pressure ◽  
Upwind Scheme ◽  
Discretization Scheme ◽  
Convection Term ◽  
Spatial Discretization ◽  
Wall Function ◽  
Steam Ejector ◽  
Near Wall

The effects of different modeling and solving approaches on the simulation of a steam ejector have been investigated with the computational fluid dynamics (CFD) technique. The four most frequently used and recommended turbulence models (standard k-ε, RNG k-ε, realizable k-ε and SST k-ω), two near-wall treatments (standard wall function and enhanced wall treatment), two solvers (pressure- and density-based solvers) and two spatial discretization schemes ( the second-order upwind scheme and the quadratic upstream interpolation for convective kinematics (QUICK) of the convection term have been tested and compared for a supersonic steam ejector under the same conditions as experimental data. In total, more than 185 cases of 17 different modeling and solving approaches have been carried out in this work. The simulation results from the pressure-based solver (PBS) are slightly closer to the experimental data than those from the density-based solver (DBS) and are thus utilized in the subsequent simulations. When a high-density mesh with y+ < 1 is used, the SST k-ω model can obtain the best predictions of the maximum entrainment ratio (ER) and an adequate prediction of the critical back pressure (CBP), while the realizable k-ε model with the enhanced wall treatment can obtain the best prediction of the CBP and an adequate prediction of the ER. When the standard wall function is used with the three k-ε models, the realizable k-ε model can obtain the best predictions of the maximum ER, and the three k-ε models can gain the same CBP value. For a steam ejector with recirculation inside the diffuser, the realizable k-ε model or the enhanced wall treatment is recommended for adoption in the modeling approach. When the spatial discretization scheme of the convection term changes from a second-order upwind scheme to a QUICK scheme, the effect can be ignored for the maximum ER calculation, while only the CBP value from the standard k-ε model with the standard wall function is reduced by 2.13%. The calculation deviation of the ER between the two schemes increases with the back pressure at the unchoked flow region, especially when the standard k-ε model is adopted. The realizable k-ε model with the two wall treatments and the SST k-ω model is recommended, while the standard k-ε is more sensitive to the near-wall treatment and the spatial discretization scheme and is not recommended for an ejector simulation.

CFD Simulation and Experimental Study on Solid-Liquid Hydrocyclone

2012 ◽  
Vol 562-564 ◽  
pp. 1606-1609
Author(s):  
Si Huang ◽  
Yue Le ◽  
Luo Li
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Experimental Study ◽  
Cfd Simulation ◽  
Separation Efficiency ◽  
Test System ◽  
Equation Model ◽  
Liquid Particle ◽  
Two Phases ◽  
Solid Liquid

This paper presents a numerical simulation and experimental study on a solid-liquid hydrocyclone. In the simulation, the standard k-ε turbulence model and the zero-equation model are employed to compute the flow field of the two phases in the hydrocyclone under different conditions, such as viscosity of the liquid, particle size and flow rate. In the experiment, a hydrocyclone is manufactured and measured for the separation efficiency and pressure drop in the test system. The simulation result of hydrocyclone performance matches well with the experimental data.

Prediction of the Flow Around an Airfoil Using a Reynolds Stress Transport Model

1995 ◽  
Vol 117 (1) ◽  
pp. 50-57 ◽  
Author(s):  
Lars Davidson
Keyword(s):  
Experimental Data ◽  
Reynolds Stress ◽  
Transport Model ◽  
Suction Side ◽  
Equation Model ◽  
Staggered Grid ◽  
Poor Agreement ◽  
Third Order ◽  
Reynolds Stress Transport Model ◽  
Quick Scheme

A second-moment Reynolds Stress Transport Model (RSTM) is used in the present work for computing the flow around a two-dimensional airfoil. An incompressible SIMPLEC code is used, employing a non-staggered grid arrangement. A third-order QUICK scheme is used for the momentum equations, and a second-order, bounded MUSCL scheme is used for the turbulent quantities. As the RSTM is valid only for fully turbulent flow, an eddy viscosity, one-equation model is used near the wall. The two models are matched along a preselected grid line in the fully turbulent region. Detailed comparisons between calculations and experiments are presented for an angle of attack of α = 13.3 deg. The RSTM predictions agree well with the experiments, and approaching stall is predicted for α = 17 deg, which agrees well with experimental data. The results obtained with a two-layer κ – ∈ model show poor agreement with experimental data; the velocity profiles on the suction side of the airfoil show no tendency of separation, and no tendency of stall is predicted.

scholarly journals Three-Dimensional Numerical Simulations of Buoyant Jets Discharged from a Rosette-Type Multiport Diffuser

2019 ◽  
Vol 7 (11) ◽  
pp. 409 ◽  
Author(s):  
Xiaohui Yan ◽  
Abdolmajid Mohammadian ◽  
Xin Chen
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Computational Cost ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Ambient Water ◽  
Mixing Processes ◽  
Buoyant Jets ◽  
Practical Applications ◽  
Good Agreement

In some outfall systems, wastewaters are discharged into ambient water bodies using rosette-type diffusers in the form of multiple buoyant jets, and it is essential to simulate their mixing characteristics for practical applications and optimal design purposes. The mixing processes of a rosette jet group are more complicated than single jets and multiple horizontal or vertical jets, and thus the existing methods cannot be effectively used to simulate their mixing and dilution properties. With the recent advancements in numerical modeling approaches, numerical simulation of wastewater jets as three-dimensional phenomena can be feasible. The present study deals with a fully three-dimensional numerical simulation for buoyant jets discharged from a rosette-type multiport diffuser, with the standard and re-normalization group (RNG) k-ε turbulence models. The simulated results are compared with experimental data, and the results show a good agreement with the experimental data, demonstrating that the numerical model is an efficient and effective tool for simulating rosette jet groups. It was also concluded that the RNG k-ε model leads to better results than the standard k-ε model with a comparable computational cost. The validated model was further utilized to investigate the influences of port inclinations on the mixing behaviors.

Void pattern fluctuation in p-AgBr interactions at 400 GeV/c

2016 ◽  
pp. 4115-4125
Author(s):  
Argha Deb
Keyword(s):  
Experimental Data ◽  
Phase Transition ◽  
Phase Space ◽  
Second Order ◽  
Hadron Phase

The event-by-event fluctuation of hadronic patterns is investigated by finding a measure of the non-hadronic regions, the voids, for the experimental data of p-AgBr interactions at 400 GeV/c considering the anisotropy of phase space. Two moments of the event-to-event fluctuation of voids, <Gq> and Sq have been calculated as defined by R. C. Hwa and Q. H. Zhang to quantify the dependence of the voids on the bin sizes. The results suggest that no quark-hadron phase transition of second order have taken place for p-AgBr interactions at 400 GeV/c. The result have been compared with the result of VENUS generated data.

Sign in / Sign up

Export Citation Format

Share Document