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Introducing Undergraduates to Advanced
Computational Software using
Practical Problems
Robert P. Hesketh
Rowan University
9:45 AM – 10:10 AM
Future of CACHE
Saturday, 8 August 2009
Use of Advanced Computing
• Are we still teaching in the 60’s?
• How many courses use advanced
software?
– Excel – all courses
– POLYMATH – some courses?
– MATLAB
– CACHE software
– Chemical Process Simulation (ASPEN etc.)
– Finite Element (Comsol/Ansys etc.)
Texts on Problem Solving
Textbooks on introducing software in ChE
• Cutlip & Shacham
• Finlayson
Features
• Practical Examples in all subjects
• How many professors use in
courses?
– Adapted more readily by recent grads
– Activation barrier for other professors
Progression of Advanced
Software Usage in Text books
• Appendix with numerical techniques
• Chapter on
advanced numerical techniques
• Textbooks with finite element/difference
examples within individual chapters
• Textbooks with examples using
commercial software (CD)
• Textbooks with web based modules
Subject Specific Texts
with Adv. Software
• Fogler: Essentials of Chemical
Reaction Engineering –
POLYMATH, MATLAB & CFD
• Process Control - MATLAB
• Fluid Mechanics
– Wilkes: Fluid Mechanics for Chemical
Engineers
– Munson: Fluid Mechanics
– Cimbala: Essentials of
Fluid Mechanics
(free FlowLab))
Educational Programs
• FlowLab – ANSYS/Fluent
– Sudden Expansion in a Pipe –
compare solutions to Blasius Correlation
– Flow Around a Cylinder –
(Produce Re vs Cd plot)
Cimbala 2008 – FlowLab in Text 2nd Ed.
• 1st Edition – last chapter only
• 2nd Edition Throughout book
• compare CFD with
analytical calculations
• emphasis on learning fluid
mechanics, with a secondary
emphasis on CFD
• Simple Geometries
• Homework problems progress in
difficulty & similar to example
John Cimbala, Introducing CFD in Undergraduate Fluid Mechanics, Çengel-Cimbala
ISTEC Meeting, Cornell University ,July 25-26, 2008, Ithaca, NY
Finite Elements at Rowan
• Junior year
– 2nd Fluids Course
– Chemical Reaction Engineering
– Engineering Clinic Projects
• Senior year
– Transport Phenomena Course
– Engineering Clinic Projects
How to Introduce?
• Use Comsol Tutorials?
– Target: professional user.
– Excellent step by step
tutorials
– Good for starting projects
– Too difficult for student
learning
• Need tutorials for students
and users unfamilar to
Adv. Software usage
Comsol Tutorials
Comsol Tutorials (Flow between Parallel Plates)
Students (And Perhaps
Professor) are baffled
Momentum Balance
Boundary Conditions ??
Rowan Method: Fluids
• Start with experiment, movie
or drawing on board
• Discuss velocity at
center and wall
• Sketch velocity profile
• Derive momentum balance
• Solve by hand Velocity of for Fully Developed Flow Between Parallel Plates
• Solve using POLYMATH
3.50E-02
3.00E-02
2.50E-02
• Solve using COMSOL
2.00E-02
Velocity (m/s)
Comsol Solution
1.50E-02 Analytical Solution
1.00E-02
5.00E-03
0.00E+00
-0.012 -0.01 -0.008 -0.006 -0.004 -0.002 0 0.002 0.004 0.006 0.008 0.01 0.012
-5.00E-03
X (m)
Flow in a Pipe! (Newtonian & Power Law)
POLYMATH Report 8.2 a&b Laminar Flow of Non-Newtonian Fluids in a Horizontal Pipe
Ordinary Differential Equations
1 d(tau_r)/d(r) = delP/L*r
2 d(vx)/d(r) = if(tau>0) then (-(tau/K)^(1/n)) else ((-tau/K)^(1/n))
3 d(vavg)/d(r) = vx*r*2/R^2
Comparison of Numerical and Analytical Solutions
to Pipe Flow (n=0.5)
0.08
0.07
0.06
Velocity (m/s)
0.05
Polymath
0.04
Analytical
0.03 Comsol
0.02
0.01
0
0 0.002 0.004 0.006 0.008 0.01
Radius (m)
Start with simple problems
• Pipe Flow
• Parallel Plates
• Falling Film
• Annular Flow
• Rotating Cylinder
• Rotating Cylinders
• Based on simple problems with
analytical solutions:
Geankoplis / Cutlip & Shacham
Challenge Problems: Fluids
• Radial Flow between
Parallel Disks
• Newtonian fluid in a parallel
- disk viscometer
• Velocity Profiles for a Wall
Suddenly Set in Motion –
Laminar Flow (C&S 8.17)
• Laminar Boundary Layer on
Flat Plate (C&S 8)
Chemical Reaction
Engineering
• COMSOL ECRE in new text
(FEMLAB ECRE in previous text)
• Special version of COMSOL
Multiphysics
– Prebuilt models (no meshing and geometry
issues)
– User can change parameters k, T,
flowrates, diffusivities, conductivities etc.
COMSOL ECRE
• Radial effects in tubular reactors
– Isothermal reactor
– Non-isothermal adiabatic reactor
– Non-isothermal reactor with isothermal cooling jacket
– Non-isothermal reactor with non-isothermal cooling
jacket.
• New Edition has tubular reactors where the flow
includes the effects of dispersion
– 1-dimensional model with Danckwerts boundary
conditions
– 1-dimensional model with upstream and downstream
sections
Advantages
• Anyone with textbook can use!
• Motivates students for later use of
commercial software
• Students can easily run models without
the frustration of solver problems
• Model Equations are written using
differential form (not vector notation)
• Can be used in transport class after
Reaction Engineering Course
Disadvantage? – not the full code
Rowan Chemical Reaction Engineering
• Used full COMSOL Code
– Isothermal reactor
• Plug flow reactor in laminar flow
• Laminar flow reactor with axial diffusion
• Laminar flow reactor with axial and radial diffusion
– Laminar Flow Reactor with
Heat Transfer Effects
• adiabatic reactor
• Non-isothermal reactor with isothermal cooling jacket
• Compared solutions to POLYMATH code for
plug flow (Solution familiar to students)
POLYMATH Report Isothermal Reactor for comparison with COMSOL
Ordinary Differential Equations 19-Apr-2006
Differential equations
1 d(FA)/d(V) = rA
2 d(FC)/d(V) = -2 * rA
3 d(FB)/d(V) = rA
Transport Course
(Senior/Grad)
• Mass, Energy and Momentum – a
natural for COMSOL
• Tutorials
• Homework Problems – similar to fluids
• Challenge Problems – similar to fluids
• Projects
Transport Projects
• Solve selected transport problems in
simple geometries.
• Compare solutions against established
correlations or published data.
• First year both laminar flow and
turbulent flow
• Subsequent years only laminar flows or
plug flow.
Transport Projects
• Fluids
– Pressure Drop in Fittings
– Flow distributors & measurement devices
– Motionless Mixers
– Free Jets and Mixing
• Mass Transfer
– Wetted wall column.
– Adsorption in a packed column.
• Heat Transfer
– Forced Convection Cooling of a Cylinder.
– Heat Transfer in non-Newtonian Fluids
Common Problems with Projects
• Concept of comparing correlations or
data to COMSOL results – problematic
for undergrads
• Turbulence
• Construction of 2-D and 3-D models
• Convergence and Meshing
• Result:
– high degree of student frustration
– Need introduction before senior year
Example Non-Newtonian Pipe flow:
Polymath is easier to use!
Annular Flow (Polymath 8.4)
• Problems at shear rate = 0
• Create two regions
• Mesh separately
• Add Artificial Diffusion
– pressure stabilization
– streamline diffusion
Needed for Professors & Students
• Examples need to be integrated with textbooks
• Tutorials Needed – Basic Problems
– Problems with analytical solutions
– Problems with empirical correlations/data
• Tutorials Needed for help with Convergence
– Help with geometry
– Solver Hints
– Explanation of techniques such as artificial diffusion
and stabilization
• Expected Result: Students learn subject matter
AND gain confidence in using advanced
numerical software
Questions
Motionless Mixers
• Used in-built laminar flow model
• Problems with turbulent flow
CoV Grid Distribution
Flow Past Banks of
Forced Convection Tubes – Aligned
Flow
Perpendicular to
Axis of Cylinder
Velocity
Temperature
Velocity Temperature
Flow Parallel
to Pipe
Velocity Temperature
Pressure Drop - Fittings
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