Fluid Flow & Heat Transfer Analysis Flashcards
7 cards from real CPCE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Fluid Flow & Heat Transfer Analysis flashcards as text
What is the role of the Boussinesq approximation in natural convection CFD simulations?
Answer: Treats density as constant except in the buoyancy term of the momentum equation
The Boussinesq approximation treats density as constant throughout except in the gravitational body force term, where density variations due to temperature drive the buoyancy force.
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.
Which phenomenon is captured by the turbulent Prandtl number in CFD heat transfer modeling?
Answer: The ratio of turbulent momentum diffusivity to turbulent thermal diffusivity
The turbulent Prandtl number (Pr_t) represents the ratio of eddy viscosity to eddy thermal diffusivity, typically assumed near 0.85-0.9 for gases in wall-bounded flows.
In CFD simulation of compressible flow, what occurs at a normal shock wave within the computational domain?
Answer: Abrupt discontinuity in velocity, pressure, and temperature
A normal shock represents an abrupt discontinuity where flow transitions from supersonic to subsonic with sudden increases in pressure, temperature, and density and decrease in velocity.
What is the primary advantage of Detached Eddy Simulation (DES) over standard RANS turbulence models?
Answer: DES resolves large-scale turbulent structures in separated flow regions
DES uses RANS near walls and switches to LES-like treatment in separated regions, better capturing large-scale unsteady turbulent structures in wakes and separated shear layers.
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.
In CFD analysis of a centrifugal pump, what reference frame technique is commonly used to simulate the rotating impeller?
Answer: Multiple Reference Frame (MRF) or rotating reference frame approach
The Multiple Reference Frame (MRF) approach models the impeller region in a rotating frame and the volute in a stationary frame, allowing steady-state solution of rotating machinery with reasonable accuracy.