Progress Through Quality Education

P. R. NarenSchool of Chemical & Biotechnology

SASTRA University

Thanjavur 613401

E-mail: prnaren@scbt.sastra.edu

at

Faculty Development Program on Computational Fluid DynamicsSchool of Mechanical Engineering

SASTRA University

Thanjavur 613401

01 June 2015

Computational Fluid DynamicsOverview, Scope and Relevance

Outline

• Objective of FDP on CFD – Genesis– Overall framework

• Glimpse of applications

• Flow Modelling – Why CFD ?– What CFD?– When CFD? – Typical Sequence of operation in CFD

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Objective of FDP

• To provide basic understanding of fundamental concepts involved in CFD

• To comprehend numerical techniques involved in CFD

• Use CFD tool to complement learning process

• CFD tool (Ansys) used for illustration

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Expected Outcome

• Should be able to describe the concepts involved in CFD simulation

• Should be able to develop CFD model for simple flow systems , simulate and better understand underlying physics

• Should be able to design and introduce a primer course of CFD for UG / PG level

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Framework of FDP

• Lectures (FN)• Hands-on Session (AN)

– Pipe flow Why simple test cases? – Flow through flat plate

• Open Interaction on Day 3 and Day 5• Wikispace [https://www.wikispaces.com]

– Online web hosting repository – classroom mgmt. system�Share files� Discussion forum

– https://sastra-fdp-cfd.wikispaces.com/ – Join code: TNRMRPJ

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Common Flow Structures

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http://www.open-ocean.org/pictures/53

http://www.flow.kth.se/?q=node/50

http://abyss.uoregon.edu/~js/glossary/boundary_layer.html

Avenues for CFD

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www.steamesteem.com/?boilers/combustion-engineering-v2m9

http://www.aeroresearch-llc.com/

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Examples Cont. …

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http://www.mentor.com/

Modelling vs. Simulation

• Modelling– Description of process / physics of a system

�mathematical expressions / entities

– Ability to comprehend the science

• Simulation – Instance of model– Output from model for particular input value

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Characteristic Length and Time Scales

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http://www.tms.org/pubs/journals/jom/1111/krajewski-1111.html

Types of Models

• Phenomenological modeling– Based on conversation laws – Flow mostly compromised – idealized

• Statistical modeling– Experiment data fitting– One or two dependent variables – Known functional relationship

• Flow Modeling– Detailed description of flow pattern in system

• Data driven modeling– Cause effect relationship with/without exact functional relationship– More state space

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Why Flow Modelling

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Why Flow Modelling

• Ideal Contactors In reality

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Flow Modelling

• Experimental FD

• Theoretical FD

• Computational FD

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Why CFD?

• Empirical procedures

• Scale up issues

• No generalization

• Investment – Man hours and Currency

• Micro/Meso scale information

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• Computational fluid dynamics (CFD) is one of the

branches of fluid mechanics that uses numerical methods

and algorithms to solve and analyze problems that involve

fluid flows.

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http://en.wikipedia.org/wiki/Computational_fluid_dynamics

Advantage CFD

• Access to flow information• Better understanding of physics• Screen large reactor choices• Efficient retrofitting solution• Learning tool - The FEEL factor • Save man hours per knowledge gained

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Outcome from CFD Analysis

• Select the best design - aid design – Performance– Capacity– Constraints

• Better understanding of flow behavior – Local flow pattern

• Predict engineering parameters– Drag coefficient– Wall shear – Pressure drop

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Framework of CFD

• Observe– Identify Physics

• Model development and discretion– Conservation equation – Model selection, Closures, BC

• Geometry– Capture the real system into digital framework

• Solve– Discretization PDE ODE Linear Eq. – Analyze and re-observe– Tune model parameters

• Transfer1-Jun-15 CFD: Overview, Scope and Relevance 20

Continuum

• Continuously fill the domain

• Knudsen number

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K nL

λ=

Knudsen

Governing Equations

• Conservation of mass

• Conservation of momentum

• Conservation of energy

• Concept of CV

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*

mlim

δ∀ → ∀

δρ =δ∀

Transport Equations

Closures

• Molecular transport mechanism• Flow regimes – Laminar/Turbulent, Shock waves• Heat transfer

• Multiphase flow• Interphase coupling

– Drag– Lift …

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Boundary Conditions and Types

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• Dirichlet– Specific value

• Neumann– Gradient specific

• Robin– Weighted value and gradient

• Cauchy– Both value and gradient

• Inlet

– Velocity/ mass/ pressure

• Outlet

– Velocity/ mass/ pressure

• Wall

– No slip/ Free slip

• Symmetric/ Periodic

All Set Go ?

• Simulate

• Numerical parameters– Choice of interpolation schemes– Relaxation factors– Errors and numerical convergence– Grid

• Physical solution

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Taylor

Commercial Tools

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• Grid Generation –Geometry Modelling– TGRID– Gambit– Ansys ICEM CFD

• Solvers– Ansys– CFX– Fluent– Star CD– Comsol– MFIX– OpenFoam– FeatFlow

Functionality of Commercial Tools

• Pre-processor– Geometry creation– Mesh – Boundary and domain specification

• Solver– Model selection– Boundary conditions– Operating conditions– Solver controls

� Convergence criteria, residual intervals

• Post processing– Contour– Vector – Data analysis

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Summary

• CFD provides insight into “flow”• Numerical solution of conservation equations • Knowledge of

– Physics– Numerical Techniques– Computers

• Enables better understanding of physics of systems– Learning tool– Retrofit tool– Design tool

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Resources

• Chung T. J. (2002) Computational Fluid Dynamics. Cambridge University Press

• Date A. W. (2005). Introduction to Computational Fluid Dynamics. Cambridge University Press

• Fox, R. O. (2003) Computational Models for Turbulent Reacting Flows. Cambridge University

Press

• Hoffmann K. A. and Chiang S. T. (2000). Computational Fluid Dynamics Vol1, 2 and 3.

Engineering Education System, Kansas, USA.

• John F. W., Anderson, J.D. (1996) Computational Fluid Dynamics: An Introduction Springer

• Patankar, S. (1980) Numerical Heat Transfer and Fluid Flow. Taylor and Francis

• Ranade, V.V. (2002). Computational Flow Modeling for Chemical Reactor Engineering,

Academic Press, New York.

• Versteeg, H.K. and Malalasekera, W. (1995) An Introduction to computational Fluid Dynamics

- The Finite Volume Method. Longman Scientific and Technical

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Web Resources

• http://www.cfd-online.com

• http://en.wikipedia.org/wiki/Computational_fluid_dynamics

• http://www.cfdreview.com/

• https://confluence.cornell.edu/display/SIMULATION/FLUENT

+Learning+Modules

• http://weblab.open.ac.uk/firstflight/forces/#

• NPTEL

– Balchandra Puranik and Atul Sharma

– Srinivaas Jayanthi

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Gratitude

• Dr. Vivek V. Ranade – My Mentor Guide and Teacher

– iFMg - Research group at NCL, Pune

• Audience

– For patient hearing and for their thirst in knowledge

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THANK YOU

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A person who never made a mistake never tried anything new

- Albert Einstein - 1879 -1955