### Table of Contents

# Finite element analysis: computer simulation software

## Fluid dynamics and mass transport

Comsol can be used to solve the Navier-Stokes equation for an arbitrary flow geometry. Here is a quick tutorial how to model water flowing between two planes.

- Open a new fluid mechanics modeling environment.
- Draw a rectangle with the rectangle tool.
- Find the drop down menus that let you edit the attributes of an element.
- Set the material inside the box to be water (viscosity, density etc.)
- Each side of the rectangle (1, 2, 3, 4) can be changed to a different B.C., e.g. inlet with velocity = 1, no-slip wall etc, outlet etc.
- Click on the “mesh” shortcut button - the program draws a mesh.
- Click on the “solve” shortcut button (looks like = sign). You will see a colorful image of the velocity field.
- Click on the line tool and make a cross section of the velocity field. It should be a parabola. Measure the dv/dx at the boundary.

## Electrostatics

Comsol will also do electrostatics calculations. For example, plot the lines of equipotential for a typical CNT transistor geometry.

## Comsol licensing

The physics department has a server running comsol. (Terminals in the computer lab on the forth floor). It is possible to buy a license for $1500 for the first year and then a $300 upgrade/support fee for subsequent years. The north-west sales rep is john.dunec@comsol.com 650-324-9935.