Mixed Deck — All CPCE Topics Flashcards

For a fin array CFD simulation, which parameter most significantly affects the overall thermal resistance?

Answer: Fin spacing and height determining flow passage and surface area

Fin spacing controls flow velocity and pressure drop while fin height determines surface area, making their combined effect the dominant factor in thermal resistance optimization.

For biomedical device CFD analysis submitted to the FDA, which guidance document outlines the recommended computational modeling and simulation framework?

Answer: FDA Guidance on Reporting of Computational Modeling Studies in Medical Device Submissions

The FDA issued specific guidance on computational modeling (including CFD) in medical device submissions, defining credibility assessment requirements.

How should Certified Professional CFD Engineer professionals handle equipment showing signs of malfunction during operation?

Answer: Immediately cease operation, secure the equipment, and report

Immediate cessation prevents safety hazards, further damage, or compromised results.

In the automotive industry, which SAE standard governs the use of CFD for aerodynamic drag coefficient (Cd) prediction and correlation with wind tunnel data?

Answer: SAE J2966

SAE J2966 provides guidelines for using CFD in vehicle aerodynamic development, including Cd prediction methodology and wind tunnel correlation requirements.

Why is mesh quality important in CFD analysis?

Answer: To enhance result accuracy and numerical stability

Mesh quality is crucial because it directly impacts the accuracy and stability of CFD simulations. A high-quality mesh, with well-shaped and appropriately sized cells, minimizes numerical errors and ensures that the discretized equations accurately represent the continuous fluid flow, preventing non-physical results or solver divergence.

What is the key characteristic of a pressure-based CFD solver compared to a density-based solver?

Answer: Uses pressure as the primary variable for incompressible and low-speed flows

Pressure-based solvers use the pressure field as the primary variable and are well-suited for incompressible and mildly compressible flows where density variations are small.

What is 'mesh aspect ratio' and what problem arises when it is excessively large?

Answer: Ratio of longest to shortest cell dimension; very high ratios can cause solver ill-conditioning and inaccuracy

Aspect ratio is the ratio of a cell's longest edge to its shortest; extremely large aspect ratios can make the discretized equations ill-conditioned and reduce solution accuracy.

Under ASME PTC 19.1, when reporting CFD validation results, which combination must be included?

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.

Why are industry standards important in engineering design?

Answer: They ensure consistent and safe design practices

Industry standards are essential in engineering design as they provide a common set of guidelines, specifications, and best practices. Adhering to these standards ensures that products, processes, and systems are consistently reliable, perform safely, and meet minimum quality requirements. This consistency helps prevent failures, reduces risks, and builds trust in engineered solutions across various sectors.

What is the MOST important factor when selecting assessment tools for CPCE certification work?

Answer: Validity, reliability, and appropriateness for the specific context

Assessment tools must be valid, reliable, and appropriate for the specific context.

Which method is commonly used to solve CFD equations numerically?

Answer: Finite Volume Method

The Finite Volume Method (FVM) is widely used in CFD because it inherently ensures the conservation of quantities like mass, momentum, and energy over each discrete control volume (cell). This property makes FVM robust and physically consistent for a broad range of fluid flow problems, leading to reliable numerical solutions.

What is a common feature of CFD software platforms?

Answer: Offer pre-processing, solving, and post-processing capabilities

CFD software platforms are designed to manage the entire simulation workflow, offering integrated capabilities for pre-processing (geometry and meshing), solving (numerical computation), and post-processing (visualization and analysis). This comprehensive approach allows users to efficiently move from problem definition to insightful results within a single environment.

Which ANSYS meshing tool is specifically designed for high-quality boundary layer mesh generation around aerodynamic surfaces?

Answer: ICEM CFD

ANSYS ICEM CFD provides advanced blocking and structured hexahedral meshing capabilities particularly suited for boundary layer-resolved aerodynamic simulations.

Which metric is used to assess spatial discretization error in CFD by comparing solutions on systematically refined grids?

Answer: Grid Convergence Index (GCI)

The Grid Convergence Index (GCI) is the standard metric recommended by ASME and AIAA to quantify spatial discretization uncertainty using Richardson extrapolation across refined grids.

In CFD residual monitoring, what do normalized residuals below 10⁻⁴ typically indicate?

Answer: Adequate convergence for most engineering applications

Normalized residuals below 10⁻⁴ are generally accepted as indicating adequate convergence for engineering-level accuracy in steady-state CFD simulations.

In what situation is a 'periodic' boundary condition used in CFD?

Answer: When the geometry and flow repeat spatially, allowing a section of the domain to represent the full geometry

Periodic boundary conditions are applied when the geometry repeats in space (e.g., a turbine blade passage or a pipe with repeating fins), so only one repeating unit needs to be simulated.

What is the MOST important reason for maintaining equipment maintenance logs in CPCE practice?

Answer: To track maintenance history, predict failures, and demonstrate compliance

Maintenance logs track history, predict failures, and demonstrate regulatory compliance.

In the context of CFD solver settings, what is 'false diffusion' and which approach minimizes it?

Answer: Numerical diffusion caused by mesh-flow misalignment with first-order schemes; minimized by higher-order schemes and flow-aligned meshes

False diffusion arises when flow crosses cell faces obliquely with first-order upwind schemes; using second-order schemes and aligning mesh with the flow reduces it.

Which parallel decomposition method in OpenFOAM divides the mesh by minimizing inter-processor boundary faces?

Answer: Scotch decomposition

Scotch decomposition uses graph partitioning to minimize the number of inter-processor boundaries, reducing communication overhead in parallel simulations.

Which property of fluid flow does Reynolds number describe?

Answer: Flow regime and transition

The Reynolds number is a dimensionless quantity that characterizes the flow regime of a fluid, indicating whether it will be laminar or turbulent. It represents the ratio of inertial forces to viscous forces, providing a critical criterion for predicting the transition from smooth, orderly flow to chaotic, mixing flow.