Turbulence and Flow Dynamics Quiz

Which of the following is NOT a characteristic of turbulent flow?

• Unsteady motion

• Regular and predictable patterns

• Three-dimensionality

• Enhanced mixing of transported quantities

What is the name of the process where energy is transferred from larger eddies to smaller eddies in turbulent flow?

• Reynolds Averaging

• Energy Dissipation

• Energy Cascade

• Vortex Breakdown

Reynolds number is used to determine:

• Flow compressibility

• Laminar or turbulent nature of flow

• Temperature gradient in a fluid

• Density variation

What is the typical critical Reynolds number for internal flow to become turbulent?

• Re > 500

• Re > 2,300

• Re > 1,000

• Re > 50,000

Which of the following defines Reynolds number?

• (μ / ρUL)

• (ρUL / μ)

• (U² / gL)

• (F / A)

What is the main goal of turbulence modeling in CFD?

• Increase computational time

• Solve molecular diffusion directly

• Approximate the effects of turbulence without resolving all scales

• Eliminate the need for boundary conditions

What does RANS stand for?

• Reynolds Analyzed Navier-Stokes

• Rapid Anisotropic Numerical Solver

• Reynolds-Averaged Navier-Stokes

• Rotational Averaged Navier Scale

In RANS modeling, the velocity U is decomposed into:

• Time and space

• Instantaneous and fluctuating components

• Turbulent and non-turbulent components

• Viscous and inertial components

What is the mathematical expression for turbulent kinetic energy k?

• ½(u'² + v'² + w'²)

• u + v + w

• μ∇²u

• ρU²

The closure problem in turbulence modeling arises because:

• The Navier-Stokes equations are complete

• Turbulence introduces additional knowns

• Reynolds stresses introduce new unknowns

• The continuity equation becomes invalid