Reading Velocity every timestep

skimmilk · July 2, 2012, 08:22

Hi,

So I'm new to using OpenFoam and C++, so pardon me if this is a very simple question. But so we've done some precomputation for the fluid fields, and they've been solved, and now I simply want to inject particles that will be affected by the said field. It's an uncoupled situation, and my mesh is dynamic (but that's already been solved, so that's not a big deal).

Anyways, so since it's uncoupled, I'm going with a lagrangian solver because I want the particle solution. Like I said, the fluid's been solved, and I can put together all the files using reconstructPar. So far, I've been able to leave out the particles and get the mesh to be read at each time step (I assume it's due to mesh.readUpdate() that I put in). I know it's fine because I can see the mesh moving the way I want in paraview. I cannot however, get U to update in the field each time. I'm basing my solver on icoUncoupledKinematicParcelFoam.

What I have tried is to put in a manual update each loop. I just copied and pasted the lines in the solver to recreate a new basicKinematicCollidingCloud each time. However, when I ran this, while the velocities looked right, my particles didn't move or age. I presume this is due to the cloud being recreated each time and the particles having to be reinjected into the new clouds at every step. I also tried changing the U into a non const field in the source code and then doing something like:

*(kinematicCloud.U()) = UatcurrentTimeStep

I think this is a good way to go, though I have been unsuccessful due to my lack of C++ experience.

Any help is appreciated! Thanks. OpenFoam 2.1.1

potentialFoam · February 15, 2016, 04:56

Dear Skimmilk,

hope your are still here at the forum ;-)
I am having the same problem, I would like to use
icoUncoupledKinematicParcelFoam
for an existing unsteady solution (gained by pimpleFoam).
Therefore, for every time step a case folder exists.
Applying
icoUncoupledKinematicParcelFoam
leads to two problems:
1.) a steady velocity field is used for the tracking of the particles
2.) I cannot set the time step for 'icoUncoupledKinematicParcelFoam' with the 'system/controlDict' file.

Has somebody more experience with 'icoUncoupledKinematicParcelFoam'?

cfdopenfoam · July 11, 2016, 08:26

dear all.

has the problem solved?

potentialFoam · July 11, 2016, 08:59

Dear Karelke,

sorry, at least I did not solve it until now...

July 2, 2012, 08:22	icoUncoupledKinematicParcelFoam solver for particles - read U each time step?	#1
skimmilk New Member Join Date: Jul 2012 Posts: 1 Rep Power: 0	Hi, So I'm new to using OpenFoam and C++, so pardon me if this is a very simple question. But so we've done some precomputation for the fluid fields, and they've been solved, and now I simply want to inject particles that will be affected by the said field. It's an uncoupled situation, and my mesh is dynamic (but that's already been solved, so that's not a big deal). Anyways, so since it's uncoupled, I'm going with a lagrangian solver because I want the particle solution. Like I said, the fluid's been solved, and I can put together all the files using reconstructPar. So far, I've been able to leave out the particles and get the mesh to be read at each time step (I assume it's due to mesh.readUpdate() that I put in). I know it's fine because I can see the mesh moving the way I want in paraview. I cannot however, get U to update in the field each time. I'm basing my solver on icoUncoupledKinematicParcelFoam. What I have tried is to put in a manual update each loop. I just copied and pasted the lines in the solver to recreate a new basicKinematicCollidingCloud each time. However, when I ran this, while the velocities looked right, my particles didn't move or age. I presume this is due to the cloud being recreated each time and the particles having to be reinjected into the new clouds at every step. I also tried changing the U into a non const field in the source code and then doing something like: (kinematicCloud.U()) = UatcurrentTimeStep I think this is a good way to go, though I have been unsuccessful due to my lack of C++ experience. Any help is appreciated! Thanks. OpenFoam 2.1.1 Last edited by skimmilk; July 3, 2012 at 03:23. Reason: changed title*

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February 15, 2016, 04:56		#2
potentialFoam Member Peter Join Date: Nov 2015 Location: Hamburg, Germany Posts: 57 Rep Power: 10	Dear Skimmilk, hope your are still here at the forum ;-) I am having the same problem, I would like to use icoUncoupledKinematicParcelFoam for an existing unsteady solution (gained by pimpleFoam). Therefore, for every time step a case folder exists. Applying icoUncoupledKinematicParcelFoam leads to two problems: 1.) a steady velocity field is used for the tracking of the particles 2.) I cannot set the time step for 'icoUncoupledKinematicParcelFoam' with the 'system/controlDict' file. Has somebody more experience with 'icoUncoupledKinematicParcelFoam'?

July 11, 2016, 08:26		#3
cfdopenfoam Member Karelke Yu Join Date: Dec 2014 Posts: 96 Rep Power: 11	dear all. has the problem solved?

July 11, 2016, 08:59		#4
potentialFoam Member Peter Join Date: Nov 2015 Location: Hamburg, Germany Posts: 57 Rep Power: 10	Dear Karelke, sorry, at least I did not solve it until now...