[tzqfly]

Hi, everyone
When I do the channel flow, I want to use the perturbU utility to initialization the velocity, but after I used it, the velocity of y direction was 0 (the boundary condition of y direction is wall, the other four is cyclic ),while the other four boundaries changed. I mean the initialized U file is not the same as 0/U file of channelFoam, in the channelFoam, the coordinates of whole direction are changed. Could someone help me?

[tzqfly]

Nobody know? It's a key question for me! If you know, Please show me!!!!Thank you!!!

[tzqfly]

Again, the problem is still about PerturbU. What I'm doing is duct flow and I search all the post in this forum,but I cannot find a perturbU file that is suitable for duct flow.
- For a channel:

http://www.cfd-online.com/OpenFOAM_D...ages/1/40.html

- For a cylinder:

http://www.cfd-online.com/OpenFOAM_D...es/1/2946.html

So, when I use perturbU, I still cannot get the initial U file what I want. I think the block is the setting of perturbUDict file or sort of things. Can anybody help me?

Thank you very much!!!
Best wishes!!!

[tzqfly]

Originally Posted by tzqfly

Again, the problem is still about PerturbU. What I'm doing is duct flow and I search all the post in this forum,but I cannot find a perturbU file that is suitable for duct flow.
- For a channel:

http://www.cfd-online.com/OpenFOAM_D...ages/1/40.html

- For a cylinder:

http://www.cfd-online.com/OpenFOAM_D...es/1/2946.html

So, when I use perturbU, I still cannot get the initial U file what I want. I think the block is the setting of perturbUDict file or sort of things. Can anybody help me?

Thank you very much!!!
Best wishes!!!

After I used PerturbU, Why what I got U file were like as following? Could someone help me?

the code are something like this:


dimensions [0 1 -1 0 0 0 0];

internalField nonuniform List<vector>
1900544
(
(0.000980532 0 1.80061e-06)
(0.000980898 0 2.75062e-06)
(0.000979948 0 1.51781e-06)
(0.000979703 0 1.42284e-06)
(0.000979633 0 2.1411e-06)
(0.000979297 0 1.83582e-06)
(0.000979054 0 1.52232e-06)
(0.000978649 0 2.20859e-06)
(0.0009784 0 2.03612e-06)
(0.000978522 0 1.2951e-06)
(0.000978036 0 1.7823e-06)
(0.000977707 0 1.9481e-06)
(0.000977864 0 1.55287e-06)
(0.000977722 0 1.57262e-06)
(0.000977115 0 2.07898e-06)
(0.00097691 0 2.1948e-06)
(0.000977213 0 1.87281e-06)
(0.00097726 0 1.83351e-06)
(0.000977235 0 1.89926e-06)
(0.000977161 0 2.05758e-06)
(0.000977201 0 2.15625e-06)
(0.000977699 0 1.7834e-06)
(0.000977475 0 2.31852e-06)
(0.000978113 0 1.7369e-06)
(0.000978239 0 1.92493e-06)
(0.00097857 0 1.75005e-06)
(0.000978775 0 1.9723e-06)
(0.00097903 0 2.50651e-06)
(0.000979366 0 1.93233e-06)
(0.00097954 0 1.41831e-06)
(0.000980082 0 2.31998e-06)
(0.000980246 0 2.0136e-06)
(0.000980303 0 1.69909e-06)
(0.000980658 0 1.90959e-06)
(0.000981243 0 2.37123e-06)
(0.000981351 0 2.27653e-06)
(0.000980627 0 1.40616e-06)
(0.000981558 0 2.23683e-06)
(0.000981414 0 2.05224e-06)
(0.000981865 0 2.46832e-06)
(0.000980872 0 1.56957e-06)
(0.000981209 0 1.96471e-06)
(0.000980994 0 1.8632e-06)
(0.000980556 0 1.53074e-06)
(0.000981179 0 2.52278e-06)
(0.000980712 0 2.24577e-06)
(0.000980068 0 1.57387e-06)
(0.000980021 0 1.98853e-06)
(0.000979682 0 1.78521e-06)
(0.000979411 0 1.7468e-06)
(0.000979168 0 1.24497e-06)
(0.0009789 0 1.66229e-06)
(0.000978717 0 1.48101e-06)
(0.000978299 0 1.91934e-06)
(0.000977927 0 2.11952e-06)
(0.000977584 0 2.24559e-06)
(0.0009771 0 2.54784e-06)
(0.000977821 0 1.52177e-06)
(0.000977351 0 1.89125e-06)
(0.000977602 0 1.55997e-06)
(0.000977596 0 1.52366e-06)
(0.000977958 0 1.17656e-06)


The y direction is always 0.

[cedric_duprat]

Dear Jason,

I guess that since last october you had time to look into the PerturbU piece of code.

If so, you might have seen that in the Dict file you have to set both streamwise and spanwise direction.

Then, in the PerturbU.C file the velocity is initialized to zero and I'm sure you have seen that only the streamwise and the spanwise directions of the velocity are modified.

So .... the initialisation you have is correct if you haven't change anything in the Dict.

Then, why the 0/U file in channelFoam is not the same, it could be because the people who wrote this file didn't use PerturbU.... maybe

if you are interested in more details on this tools, you could have a look on Eugene De Villiers phD (2006), in particular the chapter 5.1.2 called "Channel Flow Initialization".

to conclude, PerturbU is used to initialize your flow. you don't need wall normal component of the velocity to trigg your flow (laminar -> turbulent).

Best regards,

Cedric

[tzqfly]

Originally Posted by cedric_duprat

Dear Jason,

I guess that since last october you had time to look into the PerturbU piece of code.

If so, you might have seen that in the Dict file you have to set both streamwise and spanwise direction.

Then, in the PerturbU.C file the velocity is initialized to zero and I'm sure you have seen that only the streamwise and the spanwise directions of the velocity are modified.

So .... the initialisation you have is correct if you haven't change anything in the Dict.

Then, why the 0/U file in channelFoam is not the same, it could be because the people who wrote this file didn't use PerturbU.... maybe

if you are interested in more details on this tools, you could have a look on Eugene De Villiers phD (2006), in particular the chapter 5.1.2 called "Channel Flow Initialization".

to conclude, PerturbU is used to initialize your flow. you don't need wall normal component of the velocity to trigg your flow (laminar -> turbulent).

Best regards,

Cedric

Thank you for your reply and I'm sorry to reply so late cause chinese Spring Festival.

I have setted the streamwise and spanwise direction, and I'm sure my setting is right. However, the results are not I want. By the way, I decided to use map,I mean map another result.

Best wishes.

[calf.Z]

I want to use mapped for inlet boundary and initialize the velocity by perturbU. Will it be worked？Thank you.