IntroCFD.pdf

shelkenathaji@gmail.com +91 97665 39307
The CFD Technology

§ Brief History
§ Predictions Methods
§ Mathematical Modeling/Governing Equations
§ Applications
Learning Objectives

Nathaji Shelke
ü M.E. in Heat Power from Sinhgad College of Engineering
ü15+ years of Industrial Experience in CAD, FEA and CFD
üInternational Certification in software skill set
üPresented International Research papers in Singapore and Australia
üCAD: Creo 2.0, CATIA V5, UG Nx 10.0 & Solid Edge ST 7.0
üCAE: ANSYS 15.0 & Hypermesh 13.
üCFD: ANSYS FLUENT
üCORPORATE CLIENTS : Mahindra, Tata Technologies, TACO, John Deer, Johnson
Control, KPIT Cummins, Whirlpool India Ltd, Onward Technologies, iGATE, PARI,
Thermax Ltd , Applied Thermal, Kirloskar Pneumatic, AESSEAL, Anand Group,

Simulation Driven Product Development

Streamlined Workflow Strategy

What is CFD?
§ Computational Fluid Dynamics (CFD) is the science of predicting fluid flow, heat and mass transfer, chemical
reactions, and related phenomena.
§ To predict these phenomena, CFD solves equations for conservation of mass, momentum, energy etc..
§ CFD can provide detailed information on the fluid flow behavior:
• Distribution of pressure, velocity, temperature, etc.
• Forces like Lift, Drag.. (external flows, Aero, Auto..)
• Distribution of multiple phases (gas-liquid, gas-solid..)
• Species composition (reactions, combustion, pollutants..)
• Much more...
§ CFD is used in all stages of the engineering process:
§ Conceptual studies of new designs
§ Detailed product development
§ Optimization
§ Troubleshooting
§ Redesign
§ CFD analysis complements testing and experimentation by reducing total effort and cost required for
experimentation and data acquisition

How Does CFD Work?
§ ANSYS CFD solvers are based on the finite volume method
§ Domain is discretized into a finite set of control volumes
§ General conservation (transport) equations for mass, momentum, energy,
species, etc. are solved on this set of control volumes
§ Partial differential equations are discretized into a system of algebraic
equations
§ All algebraic equations are then solved numerically to render the solution
field
Control
Volume*
Equation f
Continuity 1
X momentum u
Y momentum v
Z momentum w
Energy h
Unsteady Convection Diffusion Generation

History
§ Lewis Fry Richardson in England (1881-1953) developed
the first numerical weather prediction system when he
divided physical space into grid cells and used the finite
difference method.
§ The earliest numerical solution for flow past a cylinder
was carried out in 1933 by Thom and reported in England:
§ Kawaguti in Japan obtained a similar solution for flow
around a cylinder in 1953 by using a mechanical desk
calculator, working 20 hours per week for 18 months!

§ During the 1960s, the theoretical division of NASA at Los
Alamos in the U.S. contributed numerical methods –
Particle-In-Cell (PIC), Marker-and-Cell (MAC), Vorticity-
Stream function methods, Arbitrary Lagrangian-Eulerian
(ALE) methods, The ubiquitous k - e turbulence model.
§ In the 1970s, a group working under D. Brian Spalding, at
Imperial College, London, developed – Parabolic flow
codes (GENMIX), Vorticity-Stream function based codes,
The SIMPLE algorithm , The TEACH code
§ It was in the early 1980s that commercial CFD codes came
into the open market place in a big way.

NASA’s HiMAT
§ Wind tunnel test of Preliminary design
§ $ 150,000 - redesign cost in wind tunnel test
§ $ 6,000 – redesign cost on super computer

Prediction methods
Theoretical
Calculations
Experimentation
Investigation
Computational
Fluid
Dynamics

Experimentation investigation
§ The most reliable information
§ Full-scale tests are, in most cases, prohibitively
expensive & often impossible
§ Small-scale models do not always simulate all
features of full-scale equipment
§ Difficulty in measurement
§ Errors of measuring instrument
§ Disturbance of flow due to measuring instrument

Theoretical calculations
§ It requires mathematical model rather than physical
model
§ Mathematical model consists of set of differential
equations
§ Solutions method are complicated which requires
numerical tools

CFD
§ The advent of high speed digital computer combined with
development of accurate numerical algorithms holds the
promise that implications of mathematical model can be work
out for almost any practical problem
§ Low cost
§ Speed
§ Complete information
§ Ability to simulate realistic conditions
§ Ability to simulate ideal conditions
§ Worthiness of Results depends on adequate mathematical
model & satisfactory numerical technique

Finite volume method (FVM) Finite difference method (FDM)
Numerical Solution Method

Components Of Numerical Solution
Method
§ Mathematical model
§ Discretization method
§ Coordinate & basis vector systems
§ Numerical grid
§ Finite approximation
§ Solution method
§ Convergence criteria

GDE of CFD

Conservation of Mass (Continuity equation)

Conservation of Momentum

Conservation of Energy equation

Applications

Aerospace

Orion Launch Abort Vehicle

Automotive

IC Engine

Home appliances

Pump

Valve

Turbine

Biomedical

Environmental study

How to study CFD
§ Fundamentals of FM & HT
§ Governing differential equations of CFD
§ Numerical methods for engineers
§ Finite difference & finite volume methods
§ Concept of turbulence modeling
§ Working knowledge of CFD tool like ANSYS Fluent

Summary
§ Predictions methods – Theoretical + Experimental +
CFD
§ FVM & FDM
§ Conservation of mass, momentum & energy
§ Applications: Aerospace, Auto, Pump, Valve, Home
Appliances, Biomedical and many more

IntroCFD.pdf

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