Progress Through Quality Education
P. R. NarenSchool of Chemical & Biotechnology
SASTRA University
Thanjavur 613401
E-mail: [email protected]
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