CFD Exam Preparation Questions

  1. Explain the importance of selecting an appropriate mathematical model for a numerical solution method in CFD. What factors should be considered when choosing the model?

  2. Compare and contrast the finite difference, finite volume, and finite element methods in terms of their suitability for various classes of problems in CFD.

  3. How do coordinate and basis vector systems influence the formulation of conservation equations in CFD? Provide examples of how different coordinate systems might be used for specific flow problems.

  4. Discuss the advantages and disadvantages of structured, block-structured, and unstructured grids in CFD. How does grid selection impact the accuracy and efficiency of a numerical solution?

  5. Analyze the concepts of consistency, stability, and convergence in numerical solution methods. How do these properties relate to each other, and why are they essential for accurate CFD simulations?

  6. How do conservation, boundedness, and accuracy influence the development and evaluation of numerical solution methods in CFD? Discuss the challenges in achieving these properties.

  7. Identify and explain the three types of systematic errors in numerical solutions of CFD problems. How can these errors be minimized in practice?

  8. What are the key considerations for ensuring accuracy in CFD simulations? Discuss the role of grid refinement, error estimation, and validation against experimental data.

  9. Explain the significance of the Navier-Stokes equations in fluid dynamics.

  10. Discuss the energy equation in the context of fluid mechanics, including how the dissipation function and heat transfer terms are incorporated.

  11. Derive the steady convection-diffusion equation from the transport equation, and describe the physical meaning of each term in Equation (5.1) and Equation (5.2).

  12. What are the key assumptions behind the central differencing scheme used for convection-diffusion problems?

  13. Explain how the central differencing scheme is applied to approximate the diffusive terms in the convection-diffusion equation.

  14. Discuss the numerical stability and accuracy of the central differencing scheme for convection-diffusion problems. Under what conditions might this scheme become unstable?

  15. What alternative schemes could be used to improve stability, and how do they compare with the central differencing scheme?

  16. Consider a one-dimensional convection-diffusion problem with known boundary conditions. Describe the steps you would take to apply the finite volume method to solve this problem numerically.

  17. How would you handle boundary conditions and ensure that they are correctly implemented in the discretized equations?

  18. Identify a real-world engineering problem that can be modeled using the steady convection-diffusion equation. Describe the problem and explain how the finite volume method could be used to solve it.

  19. What is the role of boundary conditions in CFD simulations, and why is their accurate implementation crucial for solving fluid flow problems?

  20. List the common types of boundary conditions used in CFD and briefly describe each one.

  21. How are inlet boundary conditions implemented for a velocity component perpendicular to the x-direction?

  22. Why is it important to select the location of the outlet boundary far from geometrical disturbances?

  23. Describe the role of pressure correction in boundary conditions, particularly at inlet and outlet boundaries. How does it ensure the overall continuity of the flow?

  24. Discuss the challenges associated with estimating turbulent kinetic energy and dissipation rate at inlet boundaries. What methods are commonly used to estimate these quantities when direct measurements are not available?

  25. Explain the no-slip condition for velocity components at solid walls and its implementation in the discretized equations.

  26. Describe the step-by-step process of implementing boundary conditions in a CFD simulation using the finite volume method.

  27. Discuss how different boundary conditions might interact in a complex flow domain, and what considerations must be made when setting them.

  28. Compare the implementation of inlet and outlet boundary conditions in terms of their mathematical treatment and impact on solution stability.

  29. What are the potential pitfalls or challenges associated with each type of boundary condition, and how can they be mitigated?

  30. Discuss the challenges of implementing boundary conditions in complex geometries, such as those with internal obstacles or irregular boundaries.

  31. Propose strategies to address these challenges and ensure accurate and stable solutions.

  32. How do these techniques contribute to the stability and accuracy of CFD simulations?

  33. Discuss why understanding error and uncertainty in CFD modeling is crucial for engineering applications. What are the potential consequences of neglecting these aspects in a commercial CFD analysis?

  34. Define the different types of errors identified in CFD modeling. Provide examples of how each type of error can manifest in a simulation.

  35. Explain the main sources of uncertainty in CFD modeling and discuss how they can affect the results of a simulation. How can these uncertainties be minimized?

  36. Differentiate between verification and validation in the context of CFD. Why are both processes essential, and how do they contribute to confidence-building in CFD results?

  37. Summarize the best practice guidelines for conducting CFD simulations. Why is adherence to these guidelines crucial for achieving reliable CFD results?

  38. Describe the techniques used to control numerical errors in CFD simulations. How can these techniques improve the quality of simulation results?