10-02-2012, 02:04 PM
Computational Fluid Dynamics
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What is CFD?
Computational Fluid Dynamics (CFD) is the science of predicting fluid flow, heat transfer, mass transfer, chemical reactions, and related phenomena by solving the mathematical equations which govern these processes using a numerical process.
The result of CFD analyses is relevant engineering data used in:
conceptual studies of new designs
detailed product development
troubleshooting
redesign
CFD analysis complements testing and experimentation.
Reduces the total effort required in the laboratory.
CFD - How It Works
Analysis begins with a mathematical model of a physical problem.
Conservation of matter, momentum, and energy must be satisfied throughout the region of interest.
Fluid properties are modeled empirically.
Simplifying assumptions are made in order to make the problem tractable (e.g., steady-state, incompressible, inviscid, two-dimensional).
Provide appropriate initial and/or boundary conditions for the problem.
An Example: Water flow over a tube bank
Goal
compute average pressure drop, heat transfer per tube row
Assumptions
flow is two-dimensional, laminar, incompressible
flow approaching tube bank is steady with a known velocity
body forces due to gravity are negligible
flow is translationally periodic (i.e. geometry repeats itself)
Advantages of CFD
Low Cost
Using physical experiments and tests to get essential engineering data for design can be expensive.
Computational simulations are relatively inexpensive, and costs are likely to decrease as computers become more powerful.
Speed
CFD simulations can be executed in a short period of time.
Quick turnaround means engineering data can be introduced early in the design process
Ability to Simulate Real Conditions
CFD provides the ability to theoretically simulate any physical condition