question about the channel395 tutorial
Hi, all
I have just installed OF-2.1.1 which contains channelFoam solver. I'm doing a channel simulation. So firstly I want to clarify the accuracy of this solver. I ran the Allrun script in the channel395 tutorial and noticed something strange. 1. As for the case, Re_tau=395, nu=2e-5m^2/s, so u_tau=7.9e-3m/s and thus the pressure gradient can be calculated, gradP=u_tau^2/h=6.24e-5m/s^2, h is the half-width of the channel,h=1m. However, when monitoring the pressure gradient, the pressure gradient varies all the time and maintains a tendency to fall down and down. I'm confused that how can we identify the solution to reach a statical turbulent flow? 2. In the tutorial case, there are 2 folders, "0" and "0.org", take a look at into the "0" folder, it can be seen that all the initial fields are specified by nonuniform values. The only utility I know is the perturbU which can generate a parabolic velocity field for channel flow, but I don't know how to generate a proper "p" or "nusgs" field. Can someone figure it out? |
After a period of searching , I continue my calculation for a much longer time, the velocity at the domain center oscillating around 0.15m/s(the Ubar=0.1335m/s), about 1.1times. So this is exactly what it should be. The first problem is solved.
However, I'm still not quite understand the second problem. How can we initialize the p ,nusgs fields? Or my misunderstanding, just perturbU required for the velocity field? |
In fact, if I use perturbU utility without change as this
Code:
// Expected turbulent Re(tau) Reynolds number with respect to utau |
Hi Huang,
Have you got the answer on the second part of your question? I'm very interested to know the answer. Thanks, Robert |
Quote:
It has been a long time after I investigated the channel flow case. In my opinion, the fields are generated by a fully developed case so that the user can quickly has an idea of the right flow field. Xianbei |
Hi Huang,
So, if the 0 folder has been defined a posteriori then what is the purpose for defining parameters in the 0.org folder? Thanks, Robert |
Quote:
|
All times are GMT -4. The time now is 02:06. |