CPCE CPCE Turbulence Modeling & Numerical Methods

Question 1

Which turbulence model is known as a two-equation model that solves transport equations for turbulent kinetic energy (k) and its dissipation rate (ε)?

Accepted Answer

k-ε model

Answer

k-ω SST

Answer

Spalart-Allmaras

Answer

Reynolds Stress Model

Question 2

What does the acronym 'DNS' stand for in the context of CFD turbulence simulation?

Accepted Answer

Direct Numerical Simulation

Answer

Dynamic Numerical Simulation

Answer

Discrete Navier-Stokes

Answer

Diffusion Noise Scheme

Question 3

The Courant-Friedrichs-Lewy (CFL) condition is primarily a stability criterion for which class of numerical methods?

Accepted Answer

Explicit time-stepping schemes

Answer

Finite Element Methods

Answer

Boundary Element Methods

Answer

Implicit steady-state solvers

Question 4

In Large Eddy Simulation (LES), what role does the Sub-Grid Scale (SGS) model play?

Accepted Answer

It models the effect of eddies smaller than the grid size

Answer

It resolves large eddies directly

Answer

It eliminates the need for a computational mesh

Answer

It replaces the Navier-Stokes equations entirely

Question 5

Which numerical discretization scheme is second-order accurate in space and is commonly used for convection terms in CFD to balance accuracy and stability?

Accepted Answer

Central differencing

Answer

First-order upwind

Answer

Quick scheme

Answer

Power-law scheme

Question 6

What is the primary advantage of the k-ω SST turbulence model over the standard k-ε model?

Accepted Answer

It performs better in adverse pressure gradient and separated flow regions

Answer

It requires no wall functions

Answer

It is computationally faster

Answer

It eliminates the need for mesh refinement near walls