MCQOPTIONS
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MCQOPTIONS
This section includes 10 Mcqs, each offering curated multiple-choice questions to sharpen your Computational Fluid Dynamics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
___________ creates a problem in the SGS models. |
| A. | Low Reynolds number flows |
| B. | High Reynolds number flows |
| C. | Anisotropic flow near the wall |
| D. | Viscous flow near the wall |
| Answer» D. Viscous flow near the wall | |
| 2. |
The SGS model uses _________ to reduce the sub-grid-scale eddy viscosity near the wall. |
| A. | van Karman’s constant |
| B. | van Driest damping |
| C. | wall function |
| D. | Leonard stresses |
| Answer» C. wall function | |
| 3. |
The Smagorinsky-Lilly SGS model is ___________ |
| A. | Dissipative |
| B. | Convective |
| C. | Diffusive |
| D. | Convective and diffusive |
| Answer» B. Convective | |
| 4. |
In the higher-order SGS model, what is the velocity scale used? |
| A. | The ratio of the SGS turbulent kinetic energy to the SGS eddy viscosity |
| B. | The product of the SGS turbulent kinetic energy and the SGS eddy viscosity |
| C. | The square root of the SGS eddy viscosity |
| D. | The square root of the SGS turbulent kinetic energy |
| Answer» E. | |
| 5. |
What is the velocity scale taken in the Smagorinsky-Lilly SGS model? |
| A. | The ratio of the length scale and the time scale |
| B. | The square of the average strain rate of the resolved flow |
| C. | The product of the length scale and the average strain rate of the resolved flow |
| D. | The square of the length scale |
| Answer» D. The square of the length scale | |
| 6. |
What is the relationship between SGS viscosity (μSGS), density (ρ), characteristic length (Δ) and the average strain rate of the resolved flow (\(\mid\overline{S}\mid \) ) in the Smagorinsky-Lilly SGS model? |
| A. | μSGS=ρ(C)2 Δ\(\mid\overline{S}\mid \) |
| B. | μSGS=ρC(Δ)2\(\mid\overline{S}\mid^2\) |
| C. | μSGS=ρ(CΔ)2\(\mid\overline{S}\mid \) |
| D. | μSGS=ρ(CΔ)2\(\mid\overline{S}\mid \) |
| Answer» E. | |
| 7. |
Which of these assumptions is made in the Smagorinsky-Lilly SGS model? |
| A. | The changes in the flow direction are slow in the resolved flow |
| B. | The changes in the cross-stream direction are slow in the resolved flow |
| C. | The changes in the flow direction are slow in the SGS eddies |
| D. | The changes in the cross-stream direction are slow in the SGS eddies |
| Answer» B. The changes in the cross-stream direction are slow in the resolved flow | |
| 8. |
The characteristic length of the SGS eddies is __________ |
| A. | half of the filter cut-off width |
| B. | the filter cut-off width |
| C. | twice the filter cut-off width |
| D. | thrice the filter cut-off width |
| Answer» C. twice the filter cut-off width | |
| 9. |
According to the Smagorinsky-Lilly SGS model, the SGS stresses depend on the ___________ |
| A. | Rate of strain of the SGS eddies |
| B. | Rate of strain of the resolved flow |
| C. | Strain of the resolved flow |
| D. | Strain of the SGS eddies |
| Answer» C. Strain of the resolved flow | |
| 10. |
The Smagorinsky-Lilly (Sub-Grid-Scale) SGS model uses ___________ |
| A. | Boussinesq hypothesis and Prandtl mixing length model |
| B. | Prandtl mixing length model and k-ε model |
| C. | k-ε model and k-ω model |
| D. | k-ω model and Boussinesq hypothesis |
| E. | SGS model uses ___________a) Boussinesq hypothesis and Prandtl mixing length modelb) Prandtl mixing length model and k-ε modelc) k-ε model and k-ω modeld) k-ω model and Boussinesq hypothesis |
| Answer» B. Prandtl mixing length model and k-ε model | |