Fluid Dynamics: k-e Turbulence Model
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Questions and Answers

What is the purpose of using the k–e turbulence model in this study?

  • To simplify the flow analysis
  • To analyze compressible flow
  • To model turbulent flow in the channel (correct)
  • To derive the energy equation
  • The Reynolds average Navier–Stokes equations are used for numerical analysis in this study.

    True

    What does a continuity equation in fluid dynamics represent?

    It represents the conservation of mass in a fluid flow.

    The transient solution of the computational fluid dynamics model involves _____ generated by the battery during discharge.

    <p>variable heat</p> Signup and view all the answers

    What convergence criteria is set for the numerical analysis in this study?

    <p>1 × 10−6</p> Signup and view all the answers

    What software was used for the computational fluid dynamics modeling?

    <p>ANSYS FLUENT</p> Signup and view all the answers

    In the standard k–e turbulence model, __ and __ are constants in the turbulent kinetic energy equation.

    <p>C, μ</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Continuity Equation = Conservation of mass in a fluid flow Navier–Stokes Equation = Governing equations for fluid motion RANS = Time-averaged equations for turbulent flow Turbulent Flow = Irregular, chaotic fluid motion</p> Signup and view all the answers

    What is primarily responsible for turbulent kinetic energy caused by mean velocity gradient?

    <p>Gk</p> Signup and view all the answers

    The turbulent kinetic energy caused by buoyancy is represented by Gb.

    <p>True</p> Signup and view all the answers

    What is the equation used to calculate turbulence viscosity (μt)?

    <p>μt = k * ε * Cμ</p> Signup and view all the answers

    The constants C1ε, C2ε, and C3ε are used as model ______ in the equations.

    <p>constants</p> Signup and view all the answers

    What term in the equation represents the contribution of undulating expansion in compressible turbulence to overall dispersion velocity?

    <p>Ym</p> Signup and view all the answers

    Thermal radiation is significant at the operating temperature of the battery.

    <p>False</p> Signup and view all the answers

    What is the main method of heat transfer from the battery pack to the cooling plate?

    <p>Heat conduction</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>σk = Turbulent Prandtl number of k Sk = User-defined resource item Cμ = Coefficient related to turbulence viscosity Sε = User-defined resource for ε</p> Signup and view all the answers

    What is the inlet flow velocity set for the flow channel?

    <p>0.1 m/s</p> Signup and view all the answers

    The outlet condition of the flow channel is set to a gauge pressure of 101325 Pa.

    <p>False</p> Signup and view all the answers

    What is the assumed initial temperature for the computational domains in the simulations?

    <p>298.15 K</p> Signup and view all the answers

    The transfer equation used in ANSYS FLUENT for thermal analysis is based on the __________ model.

    <p>standard k-e</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>ρ = Density (kg/m3) μ = Viscosity (Pa·s) V = Flow velocity (m/s) P = Pressure (Pa)</p> Signup and view all the answers

    What method is used for velocity pressure coupling in the analysis?

    <p>Semi-implicit method</p> Signup and view all the answers

    The turbulent viscosity is represented as μt in the governing equations.

    <p>True</p> Signup and view all the answers

    What is the Reynolds stress gradient represented by in the governing equations?

    <p>λ</p> Signup and view all the answers

    Study Notes

    Turbulence Modeling and Analysis

    • Utilizes standard k–e turbulence model, specifically designed for turbulent fluid flow due to vortex generator.
    • Incorporates enhanced wall treatment, emphasizing the complexity of analytical turbulence solutions.
    • Turbulence viscosity (μt) is defined as μt = Cμρ/ε, where C and μ are constants.

    Computational Fluid Dynamics (CFD) Model

    • ANSYS FLUENT chosen for its flexibility in modeling complex fluid dynamics.
    • Numerical analysis involves continuity and Navier–Stokes equations, moving towards a steady-state solution.
    • Convergence criteria established with residuals reduced to 1 × 10^−6 for continuity, momentum, and energy equations.

    Boundary Conditions and Thermal Analysis

    • Model operates under transient conditions due to variable heat generation from battery discharge.
    • Heat is transferred from the battery to the cooling plate, followed by absorption into the coolant.
    • Inlet flow velocity is set to 0.1 m/s with outlet maintained at gauge pressure of 0 Pa.
    • Initial and ambient temperatures assumed at 298.15 K for all simulations.

    Grid Independence and Model Setup

    • 3D modeling of the liquid cooling system (BTMS) conducted using SPACECLAIM with mesh module for grid division.
    • Fluent employed for calculating the 3D heat flow coupling model due to the complexity of the channel shape.
    • The semi-implicit method of pressure connection equation is utilized for velocity-pressure coupling.

    Heat Generation Rate

    • Battery heat generation rates assessed under various charging scenarios, indicating performance variability and importance of thermal management in battery systems.

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    Description

    This quiz explores the standard k-e turbulence model and its application in fluid dynamics, particularly focusing on turbulent flow in the presence of a vortex generator. Understand key concepts such as turbulent viscosity and enhanced wall treatment. Test your knowledge of the underlying principles that govern turbulent flow in channels.

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