# COMSOL Blog

## CFD Postprocessing

Postprocessing | Posted on January 14th, 2013 by

We have written several blog posts on postprocessing already, but none detailing postprocessing for CFD. Postprocessing has always been an important part of my teachings, as you learn how to use COMSOL Multiphysics while also gaining insight into the physics at hand. I would like to share with you part of the classwork I proposed when teaching a CFD training course not long ago.

### Visualizing Fluid Flow — Postprocessing Examples and Hints

Our multiphysics training courses cover the whole simulation process, but I especially like the postprocessing step because that’s when you are able to unveil unexpected effects.

Below, I will present a series of examples and postprocessing hints on how to create them on your own. To the left there are images with captions explaining the type of simulation and the physical quantities visualized. The “Results” node is the place where all the postprocessing happens in COMSOL Multiphysics. To the right of each postprocessing example I’ve highlighted which features are needed to produce the result.

I suggest you open COMSOL Multiphysics, pick the appropriate model from the Model Library or create one from scratch, try out my examples, and share your postprocessing results with the COMSOL Community by uploading them to the Model Exchange.

#### Solution 1

Postprocessing example 1: This model simulates the time-dependent flow past a cylinder. The velocity field magnitude at different time steps is shown.

#### Solution 2

Postprocessing example 2: Steady flow over a backstep followed by a counter-clockwise rotating cylinder. Velocity field magnitude and vectors along a cut line are shown.

#### Solution 3

Postprocessing example 3: Steady flow over a backstep. Laminar and turbulent recirculation zones and velocity profiles are shown.

#### Solution 4

Postprocessing example 4: Steady flow in a circular pipe. The axial component of the turbulent fully developed velocity profile is shown and compared to the laminar case and 1/7 power law.

COMSOL Multiphysics’ capabilities also cover 3D postprocessing as you can see from the velocity profile within the cooling channel of a circuit board.

Velocity profile within the cooling channel of a circuit board

Last year, my colleague Bethany ran a postprocessing video series here on the blog, and I just watched them all again. I suggest you watch them too — they really are a great resource with lots of useful tips on how to visualize simulation results.