some questions about the tutorials of OpenFOAM-2.4.0-MNF

[zaixi-wei]

Hi, Prof.cragwhite
I'am learning OpenFOAM-2.4.0-MNF now,some questions about tutorials/dsmcfoamplus/collisionRateTest,I run this tutorial without any changes,the simulation results not same as Aanlytical results.but simulation results/Aanlytical results always equal to sqrt(2).I want to know why.It's because of consider the relative velocity between molecules?
sorry to distrub you,and thank you very much for your answers.

[craigwhite87]

I'm not able to replicate this. Using Equation 4.78 from Bird's 1994 book, I calculate a collision rate of 3.580656e22 per unit volume per unit time for the oxygen gas as set up in the tutorial case. The measurement class returns a value of 3.5803527292e+22 per unit volume per unit time, which gives a difference of 0.0085%. Have you double checked your calculation of the analytical solution?

[zaixi-wei]

I'm not able to replicate this. Using Equation 4.78 from Bird's 1994 book, I calculate a collision rate of 3.580656e22 per unit volume per unit time for the oxygen gas as set up in the tutorial case. The measurement class returns a value of 3.5803527292e+22 per unit volume per unit time, which gives a difference of 0.0085%. Have you double checked your calculation of the analytical solution?

First,Thanks for your answers,it's very helpful to me.
By the way ,coud I learn more about collisionRateTest?such as boundary conditions and simulation process .