Turbulent flow modeling quiz

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Turbulence model uses of a mathematical model to predict the effects of turbulence on fluid flows.
Additional stress due to turbulent diffusion is modeled using eddy viscosity and mean stress tensor
Turbulent flows are found most real-life scenarios, flow over a vehicle or train, flow of blood through the cardiovascular system, and airflow over an aircraft wing, the re-entry of space vehicle

Created on December 04, 2022 By

Dr. Sharad Pachpute

Important Questions on Turbulent Flows Modelling

This quiz will check your basic understanding of turbulent flows.

Questions on turbulent models (RANS and LES) and DNS are also added in the quiz.

Try to attempt all the questions.

For any query you can email: cfdflwoengineering@gmail.com

1 / 12

To capture anisotropic Turbulent stress near the curved surface, which of following turbulent model is more suitable

Seven Equations RANS Model

k -ε Turbulent Model

k -ω Turbulent Model

One Equation Model

2 / 12

To capture turbulent flow correctly over a circular cylinder with less computational effort, which of following turbulent model is used in RANS family

Spalart–Allmaras model

k-ε Turbulent Model

SST k-ω Model

7 Equations Turbulent Model

3 / 12

For two equation k - ω turbulent flow, ω represents the following:

Specific dissipation rate

Frequency of fluctuation

Square root of enstropy of fluctuating part

All the above

4 / 12

In two equation turbulent flow (k-ε), the ε represents

Dissipation of heat energy

Dissipation of turbulent kinetic energy

Loss of Pressure Energy

Increase of Turbulent Kinetic Energy

5 / 12

For two equations (k-ε )turbulent modelling which equations are solved

Reynolds Averaged Navier stokes Equations (RANSE)

Instantaneous Navier stokes Equations

Fluctuating Navier stokes Equations

Steady state Navier stokes Equations

6 / 12

In the turbulent flow, the shear stress is increased due to

Density of fluid

Eddy viscosity of the fluid

Dynamic viscosity of fluid

Kinematic viscosity of fluid

7 / 12

In the turbulent boundary layer of internal pipe flow, the thickness of laminar sublayer is given as δ

5 (ν/u*)

11.6 (ν/u*)

20 (ν/u*)

(ν/u*)

8 / 12

For flow over a flat plate, the boundary layer thickness (δ) for turbulent flow at a distance x with Reynolds number Re_x is directly proportional to

Reynolds Number, Rex

(Rex)^0.2

Distance from leading edge, X

Density

9 / 12

In the turbulent flow, the shear stress is increased due to

Density of fluid

Eddy viscosity of the fluid

Dynamic viscosity of fluid

Kinematic viscosity of fluid

10 / 12

The critical Reynolds number for a particular geometry and fluid properties is essential because it determine

Inlet conditions

Transition region between laminar and turbulent layer

Thickness of boundary layer thickness

Fluxes near wall

11 / 12

The critical Reynolds number defined based on the pipe diameter (D) for flow through a circular pipe for turbulent flow

Re > 5000

Re > 3000

Re > 2300

Re > 10000

12 / 12

For flow over a flat surface, the flow is said to be fully developed turbulent flow when Reynolds number defined on inlet velocity (U) and length from leading edge (L)

Re < 10^3

Re > 10^4

Re > 3 x 10^3

Re > 5 x 10^3

Your score is

The average score is 56%

What are turbulent flow models?

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