CPCE Industry Standards & Application in Engineering Design 2 — Questions and Answers
Question 1: According to ASME V&V 20, what is the primary purpose of validation in CFD simulations?
- To verify that equations are solved correctly
- To assess how accurately a model represents physical reality (Correct answer)
- To check grid independence of the solution
- To confirm software installation is correct
Correct answer: To assess how accurately a model represents physical reality
ASME V&V 20 defines validation as the process of determining how accurately a computational model represents the real physical system.
Question 2: Which AIAA standard provides guidelines for assessment of experimental uncertainty in CFD validation experiments?
- AIAA G-077 (Correct answer)
- AIAA R-004
- AIAA S-071
- AIAA G-003
Correct answer: AIAA G-077
AIAA G-077 provides guidelines for the estimation and reporting of uncertainty in wind tunnel testing used for CFD validation.
Question 3: In the context of ISO 9001:2015, which element is most critical when establishing a CFD simulation workflow for aerospace components?
- Maximizing solver iteration counts
- Documenting process controls and traceability (Correct answer)
- Using the highest available mesh density
- Selecting proprietary software only
Correct answer: Documenting process controls and traceability
ISO 9001:2015 requires documented information for process control and traceability to ensure quality management system compliance.
Question 4: What does the concept of 'numerical diffusion' relate to in CFD industry practice and mesh design standards?
- Diffusion of thermal energy through solid walls
- Artificial smoothing introduced by low-order discretization schemes (Correct answer)
- Physical mass diffusion in multi-species flows
- Pressure diffusion in incompressible solvers
Correct answer: Artificial smoothing introduced by low-order discretization schemes
Numerical diffusion is a truncation error artifact of low-order upwind schemes that artificially smears gradients, addressed by using higher-order schemes or finer meshes.
Question 5: Under ASME PTC 19.1, when reporting CFD validation results, which combination must be included?
- Mesh count and CPU hours only
- Bias error, precision error, and total uncertainty (Correct answer)
- Reynolds number and Mach number only
- Software version and license cost
Correct answer: Bias error, precision error, and total uncertainty
ASME PTC 19.1 requires reporting of both bias and precision error components to fully characterize total measurement uncertainty.
Question 6: Which regulatory body requires CFD analysis to meet DO-160 environmental conditions for aircraft system certification?
- EPA
- FAA (Correct answer)
- OSHA
- IEEE
Correct answer: FAA
The FAA mandates that aircraft systems, including thermal and fluid analyses supporting certification, comply with DO-160 environmental conditions.
Question 7: In industrial CFD practice, what is the primary function of a 'topology-preserving' mesh generation approach per NAFEMS best practice?
- Reducing total mesh element count
- Maintaining geometric feature fidelity during remeshing (Correct answer)
- Increasing solver convergence speed
- Eliminating boundary layer cells
Correct answer: Maintaining geometric feature fidelity during remeshing
Topology-preserving meshing ensures that geometric features such as edges, corners, and curvature are accurately represented without degradation during mesh generation.
CPCE Industry Standards & Application in Engineering Design 2
According to ASME V&V 20, what is the primary purpose of validation in CFD simulations?