The Effect and Application of Different Turbulence Models on the Design of Inertial Stage

2011 ◽  
Vol 230-232 ◽  
pp. 405-409
Author(s):  
Zhong Yi Wang ◽  
Jia Han ◽  
Tao Sun ◽  
Yun Liang Yu
Keyword(s):  
Numerical Simulation ◽  
Model Selection ◽  
Standard Model ◽  
Reference Frame ◽  
Reynolds Stress ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Resistance Characteristic ◽  
The Standard Model

The numerical simulation of the resistance characteristics of the inertial stage had been researched with different turbulence models, and the resistance characteristic computation curves of the inertial stage with different turbulence models have been obtained. Then curves contrasted with the actual value from experiments. The results show that the error of the Standard model is a little larger, but results of the RNG and Reynolds Stress are comparatively accurate. It has provided the reference frame of the turbulence model selection when the numerical simulation of the inertial stage is conducted.

The Influence of Turbulence Model Selection and Leakage Considerations on CFD Simulation Results for a Centrifugal Pump

2012 ◽  
Vol 594-597 ◽  
pp. 1940-1944
Author(s):  
Han Liu ◽  
Hua Chen Pan
Keyword(s):  
Numerical Simulation ◽  
Model Selection ◽  
Centrifugal Pump ◽  
Turbulence Model ◽  
Cfd Simulation ◽  
Turbulence Models ◽  
Leakage Flow ◽  
Pump Performance ◽  
Simulation Results

A commercial CFD software was used to simulate and predict a centrifugal pump performance. In this paper，the influences on the numerical simulation results using different turbulence models and different leakage flow assumptions were studied. The simulations are based on RANS with the and SST turbulence models. It is found that SST turbulence is better. Also the influence of the leakage flow was studied.

Numerical Simulation Analysis of Car Overtaking on SST Turbulence Model

2014 ◽  
Vol 628 ◽  
pp. 270-274
Author(s):  
Yi Bin He ◽  
Qi Zhi Shen
Keyword(s):  
Numerical Simulation ◽  
Numerical Experiment ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Simulation Analysis ◽  
Turbulence Models ◽  
Force Coefficient ◽  
Side Force ◽  
Sst Turbulence Model ◽  
Side Force Coefficient

Thebased SST (shear strain transport) turbulence model combines the advantages of and turbulence models and performs well in numerical experiment. In the paper, the SST turbulence model is applied to model vehicle overtaking process with numerical simulation technology. The change graph of drag coefficient and side force coefficient are gained. Analysis of the phenomena is presented at the end.

Comparison of Two Two-Equation Turbulence Model Used for the Numerical Simulation of Underwater Ammunition Fuze Turbine Flow Field

2012 ◽  
Vol 591-593 ◽  
pp. 1968-1972
Author(s):  
De Zhang Shen ◽  
He Zhang ◽  
Hao Jie Li
Keyword(s):  
Numerical Simulation ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Axial Pressure ◽  
Two Phase ◽  
Speed Increase ◽  
Pressure Coefficients ◽  
Surface Pressure Distribution ◽  
Calculation Results ◽  
Distribution Trends

To figure out the problem of turbulence simulation of underwater ammunition fuze turbine numerical simulation, respectively, realizable k-ε turbulence model and SST k-ω turbulence model are used for two-phase flow numerical simulation of the turbine rotation. The analysis compared the calculation results of the two turbulence models. The results showed that: the cavitation scale obtained from realizable k-ε turbulence model is shorter than that of SST k-ω turbulence model; turbine surface pressure distribution trends are similar of this two model, the results of realizable k-ε turbulence model are bigger than SST k-ω turbulence model; the turbine axial pressure coefficients using realizable k-ε turbulence model are also bigger than that of SST k-ω turbulence model, and the deviation increases with the speed increase.

scholarly journals ENVIRONMENTAL FLOW AND CONTAMINANT TRANSPORT MODELING IN THE AMAZONIAN WATER SYSTEM BY USING Q3DRM1.0 SOFTWARE

2020 ◽  
Vol 5 (12) ◽  
pp. 377-391
Author(s):  
Li-ren Yu ◽  
Jun Yu
Keyword(s):  
Numerical Simulation ◽  
Contaminant Transport ◽  
Turbulence Model ◽  
Environmental Flows ◽  
Water System ◽  
Turbulence Models ◽  
Environmental Flow ◽  
Turbulence Closure ◽  
Strong Mixing ◽  
Closure Models

This paper reports a fine numerical simulation of environmental flow and contaminant transport in the Amazonian water system near the Anamã City, Brazil, solved by the Q3drm1.0 software, developed by the Authors, which can provide the different closures of three depth-integrated two-equation turbulence models. The purpose of this simulation is to refinedly debug and test the developed software, including the mathematical model, turbulence closure models, adopted algorithms, and the developed general-purpose computational codes as well as graphical user interfaces (GUI). The three turbulence models, provided by the developed software to close non-simplified quasi three-dimensional hydrodynamic fundamental governing equations, include the traditional depth-integrated two-equation turbulence   model, the depth-integrated two-equation turbulence model, developed previously by the first Author of the paper, and the depth-integrated two-equation turbulence   model, developed recently by the Authors of this paper. The numerical simulation of this paper is to solve the corresponding discretized equations with collocated variable arrangement on the non-orthogonal body-fitted coarse and fine two-levels’ grids. With the help of Q3drm1.0 software, the steady environmental flows and transport behaviours have been numerically investigated carefully; and the processes of contaminant inpouring as well as plume development, caused by the side-discharge from a tributary of the south bank (the right bank of the river), were also simulated and discussed in detail. Although the three turbulent closure models, used in this calculation, are all applicable to the natural rivers with strong mixing, the comparison of the computational results by using the different turbulence closure models shows that the turbulence   model with larger turbulence parameter provides the possibility for improving the accuracy of the numerical computations of practical problems.

A New Unsteady-Based Turbulence Model to Predict Shear Layer Rollup and Breakdown

2004 ◽  
Author(s):  
D. Scott Holloway ◽  
James H. Leylek
Keyword(s):  
Shear Layer ◽  
Reynolds Stress ◽  
Turbulence Model ◽  
Turbine Blades ◽  
Turbulence Models ◽  
Separated Flow ◽  
Leading Edge ◽  
Tip Clearance ◽  
Aircraft Carrier ◽  
Flow Through

This paper documents the computational investigation of the unsteady rollup and breakdown of a turbulent separated shear layer. This complex phenomenon plays a key role in many applications, such as separated flow at the leading edge of an airfoil at off-design conditions; flow through the tip clearance of a rotor in a gas turbine; flow over the front of an automobile or aircraft carrier; and flow through turbulated passages that are used to cool turbine blades. Computationally, this problem poses a significant challenge in the use of traditional RANS-based turbulence models for the prediction of unsteady flows. To demonstrate this point, a series of 2-D and 3-D unsteady simulations have been performed using a variety of well-known turbulence models, including the “realizable” k-ε model, a differential Reynolds stress model, and a new model developed by the present authors that contains physics that account for the effects of local unsteadiness on turbulence. All simulations are fully converged and grid independent in the unsteady framework. A proven computational methodology is used that takes care of several important aspects, including high-quality meshes (2.5 million finite volumes for 3-D simulations) and a discretization scheme that will minimize the effects of numerical diffusion. To isolate the shear layer breakdown phenomenon, the well-studied flow over a blunt leading edge (Reynolds number based on plate half-thickness of 26,000) is used for validation. Surprisingly, none of the traditional eddy-viscosity or Reynolds stress models are able to predict an unsteady behavior even with modifications in the near-wall treatment, repeated adaption of the mesh, or by adding small random perturbations to the flow field. The newly developed unsteady-based turbulence model is shown to predict some important features of the shear layer rollup and breakdown.

scholarly journals Evaluation of the Turbulence Model Influence on the Numerical Simulation of Cavitating Flow with Emphasis on Temperature Effect

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 997
Author(s):  
Yilin Deng ◽  
Jian Feng ◽  
Fulai Wan ◽  
Xi Shen ◽  
Bin Xu
Keyword(s):  
Numerical Simulation ◽  
Temperature Effect ◽  
Turbulence Model ◽  
Numerical Solutions ◽  
Turbulent Viscosity ◽  
Turbulence Models ◽  
Correction Method ◽  
Cavitating Flow ◽  
Density Correction ◽  
Different Temperatures

The aim of this paper is to investigate the influence of different turbulence models (k−ε, RNG k−ε, and SST k−ω) on the numerical simulation of cavitating flow in thermosensitive fluid. The filter-based model and density correction method were employed to correct the turbulent viscosity of the three turbulence models. Numerical results obtained were compared to experimental ones which were conducted on the NACA0015 hydrofoil at different temperatures. The applicability of the numerical solutions of different turbulence model was studied in detail. The modified RNG k−ε model has higher accuracy in the calculation of cavitating flow at different temperatures.

scholarly journals Selecting a k-ε turbulence model for investigating n-decane combustion in a diesel engine combustion chamber

2019 ◽  
Vol 7 (2) ◽  
pp. 80-87
Author(s):  
Andrii Avramenko
Keyword(s):  
Numerical Simulation ◽  
Diesel Engine ◽  
Combustion Chamber ◽  
Turbulent Flows ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Toxic Substances ◽  
Engine Combustion ◽  
Experimental Findings ◽  
The Impact

The results of a comparative numerical simulation of combustion and formation of toxic substances in a diesel engine combustion chamber are given. Experimental findings were used to identify the mathematical models. The impact of the standard, RNG and realizable k-ε turbulence models on the accuracy of numerical simulation of combustion and the formation of toxic substances was studied. The realizable k-ε turbulence model was shown to provide a closer agreement of computational and experimental data during simulation of the diesel engine process when turbulent flows are described.

scholarly journals Mass at rest after quantum information

2020 ◽  
Author(s):  
Vasil Dinev Penchev
Keyword(s):  
General Relativity ◽  
Quantum Information ◽  
Standard Model ◽  
Quantum System ◽  
Reference Frame ◽  
Big Bang ◽  
Single Quantum ◽  
The Standard Model ◽  
The Axiom Of Choice ◽  
The Big Bang

The way, in which quantum information can unify quantum mechanics (and therefore the Standard model) and general relativity, is investigated. Quantum information is defined as the generalization of the concept of information as to the choice among infinite sets of alternatives. Relevantly, the axiom of choice is necessary in general. The unit of quantum information, a qubit is interpreted as a relevant elementary choice among an infinite set of alternatives generalizing that of a bit. The invariance to the axiom of choice shared by quantum mechanics is introduced: It constitutes quantum information as the relation of any state unorderable in principle (e.g. any coherent quantum state before measurement) and the same state already well-ordered (e.g. the well-ordered statistical ensemble of the measurement of the quantum system at issue). This allows of equating the classical and quantum time correspondingly as the well-ordering of any physical quantity or quantities and their coherent superposition. That equating is interpretable as the isomorphism of Minkowski space and Hilbert space. Quantum information is the structure interpretable in both ways and thus underlying their unification. Its deformation is representable correspondingly as gravitation in the deformed pseudo-Riemannian space of general relativity and the entanglement of two or more quantum systems. The Standard model studies a single quantum system and thus privileges a single reference frame turning out to be inertial for the generalized symmetry U(1)XSU(2)XSU(3) “gauging” the Standard model. As the Standard model refers to a single quantum system, it is necessarily linear and thus the corresponding privileged reference frame is necessary inertial. The Higgs mechanism U(1) → U(1)XSU(2) confirmed enough already experimentally describes exactly the choice of the initial position of a privileged reference frame as the corresponding breaking of the symmetry. The Standard model defines ‘mass at rest’ linearly and absolutely, but general relativity non-linearly and relatively. The “Big Bang” hypothesis is additional interpreting that position as that of the “Big Bang”. It serves also in order to reconcile the linear Standard model in the singularity of the “Big Bang” with the observed nonlinearity of the further expansion of the universe described very well by general relativity. Quantum information links the Standard model and general relativity in another way by mediation of entanglement. The linearity and absoluteness of the former and the nonlinearity and relativeness of the latter can be considered as the relation of a whole and the same whole divided into parts entangled in general

Numerical analysis for wake flow field of Ahmed model based on a nonlinear-LRN/DES turbulence model

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Le Dian Zheng ◽  
Yi Yang ◽  
Guang Lin Qiang ◽  
Zhengqi Gu
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Reynolds Stress ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Aerodynamic Characteristics ◽  
Wake Flow ◽  
Field Analysis ◽  
Content Type ◽  
Des Model

Purpose This paper aims to propose a precise turbulence model for automobile aerodynamics simulation, which can predict flow separation and reattachment phenomena more accurately. Design/methodology/approach As the results of wake flow simulation with commonly used turbulence models are unsatisfactory, by introducing a nonlinear Reynolds stress term and combining the detached Eddy simulation (DES) model, this paper proposes a nonlinear-low-Reynolds number (LRN)/DES turbulence model. The turbulence model is verified in a backward-facing step case and applied in the flow field analysis of the Ahmed model. Several widely applied turbulence models are compared with the nonlinear-LRN/DES model and the experimental data of the above cases. Findings Compared with the experimental data and several turbulence models, the nonlinear-LRN/DES model gives better agreement with the experiment and can predict the automobile wake flow structures and aerodynamic characteristics more accurately. Research limitations/implications The nonlinear-LRN/DES model proposed in this paper suffers from separation delays when simulating the separation flows above the rear slant of the Ahmed body. Therefore, more factors need to be considered to further improve the accuracy of the model. Practical implications This paper proposes a turbulence model that can more accurately simulate the wake flow field structure of automobiles, which is valuable for improving the calculation accuracy of the aerodynamic characteristics of automobiles. Originality/value Based on the nonlinear eddy viscosity method and the scale resolved simulation, a nonlinear-LRN/DES turbulence model including the nonlinear Reynolds stress terms for separation and reattachment prediction, as well as the wake vortex structure prediction is first proposed.

scholarly journals Comparison of Different Turbulence Models for Numerical Simulation of Pressure Distribution in V-Shaped Stepped Spillway

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Zhaoliang Bai ◽  
Jianmin Zhang
Keyword(s):  
Numerical Simulation ◽  
Pressure Distribution ◽  
Flow Pattern ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Flow Regimes ◽  
Stepped Spillway ◽  
Stepped Spillways

V-shaped stepped spillway is a new shaped stepped spillway, and the pressure distribution is quite different from that of the traditional stepped spillway. In this paper, five turbulence models were used to simulate the pressure distribution in the skimming flow regimes. Through comparing with the physical value, the realizablek-εmodel had better precision in simulating the pressure distribution. Then, the flow pattern of V-shaped and traditional stepped spillways was given to illustrate the unique pressure distribution using realizablek-εturbulence model.

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