Comsol Multiphysics

Lecture 11: Introduction to COMSOL Multiphysics Simulations

Dr. Ryan D. Sochol

ME138/238 Micro/Nano Mechanical Systems Laboratory

Department of Mechanical Engineering University of California, Berkeley

Dr. Ryan D. Sochol Lecture 11: Introduction to COMSOL Multiphysics Simulations March 4, 2013

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Outline • Example: Micropost Arrays

for Cell Mechanics ◦ Uniform Micropost Arrays

to Detect Cellular Traction Forces

• COMSOL Multiphysics v3.5 Demonstration ◦ Micropost Force-Displacement Simulation ◦ Microfluidics Simulations


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Background • Uniform Micropost Arrays ◦ Cellular Traction Force

Quantification

J.L. Tan, J. Tien, D.M. Pirone, D.S. Gray, K. Bhadriraju & C.S. Chen, PNAS (2003).


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Introduction

10 µm

• Uniform Micropost Arrays ◦ Cellular Traction Force

Quantification

J.L. Tan et al., PNAS (2003). (Images) R.D. Sochol, S. Li, L. Lin et al., Soft Matter (2011).

Micropost Stiffness


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Micropost Arrays to Direct Stem Cell Fate

Jianping Fu, Y.-K. Wang, M.T. Yang, R.A. Desai, X. Yu, Z. Liu & Christopher S. Chen, Nature Methods (2010).


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Micropost Arrays to Direct Stem Cell Fate

EXAMPLE for COMSOL

Jianping Fu, Y.-K. Wang, M.T. Yang, R.A. Desai, X. Yu, Z. Liu & Christopher S. Chen, Nature Methods (2010).


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COMSOL Multiphysics v3.5 Demonstration • Determine the Type of Model


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COMSOL Multiphysics v3.5 Demonstration • Determine the Type of Model


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COMSOL Multiphysics v3.5 Demonstration • Build a Cylinder


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COMSOL Multiphysics v3.5 Demonstration • Build a Cylinder


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COMSOL Multiphysics v3.5 Demonstration • Input the “Subdomain Settings” of the Material

Note: These are material properties the authors used for PDMS; however, ν = 0.499 was used instead of ν = 0.5 to avoid crashing COMSOL


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COMSOL Multiphysics v3.5 Demonstration • Input the “Boundary Settings” (e.g., constraint)


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COMSOL Multiphysics v3.5 Demonstration • Input the “Boundary Settings” (e.g., load)

Note: 20 nN distributed over a face with Diameter = 2 µm is ~6.4x103 N/m2


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COMSOL Multiphysics v3.5 Demonstration • Create a “Mesh”

Note: The type and size of mesh can influence the final solution. Overall, higher mesh sizes are better, but increase solution times.


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COMSOL Multiphysics v3.5 Demonstration • Click “Solve Problem”


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COMSOL Multiphysics v3.5 Demonstration • More Meshed “Elements” = Longer “Solution Time”

Note: More Meshed Elements = Higher Accuracy; Balance Time vs. Accuracy


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COMSOL Multiphysics v3.5 Demonstration • Input the “Plot Parameters” (under “Postprocessing”)

Note: The initial “Plot Parameters” are rarely ideal.


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The deformed shape can be plotted. Note: The scale factor can be set to “1” to see the ‘exact’ deformation.


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The number of ‘Slices’ can be increased. A variety of properties can be plotted. Note: Too many ‘Slices’ can cause COMSOL to crash.


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Finally, we have a plot similar to Fig. 1a in the Nature Methods paper.


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COMSOL Multiphysics v3.5 Demonstration • Problem? 0.3 MPa or 0.3 Pa?


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COMSOL Multiphysics Simulations • Complex Microstructures

Displacement Fields (μm); Load = 50 nN

R.D. Sochol, S. Li, L. Lin, S. Takeuchi et al., IEEE MEMS 2013.


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Additional COMSOL Simulation Examples • Microfluidic Simulations

Arrayed Microposts Reagent 1

Reagent 2

Ryan D. Sochol, S. Li, L.P. Lee & Liwei Lin, Lab on a Chip (2012).


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α

FAILURE



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Bead Releases to Promote Fluid Flow

Pressure Drop Fluidic Resistance

Ryan D. Sochol, Luke P. Lee, Liwei Lin et al., IEEE MEMS 2012.

Comsol Multiphysics

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