Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Changing the boundary condition during a transient solution
Posted Oct 31, 2015, 3:11 p.m. EDT 2 Replies
Please login with a confirmed email address before reporting spam
Hello every body,
suppose that I have a channel through which water flows. at first, the top and bottom walls of the channel are heated by a temperature of for instance 400 K. I want to run this case for, "for example" 60 seconds but, "for example" for first 10 seconds of the simulation, the boundary condition is a constant temperature heated wall (of course my real boundary condition for this 10 seconds should be run as transient not stationary) and for the 50 seconds of the remaining simulation the heated wall boundary condition is off and the boundary condition is changed to no slip wall. I want to do this to see the effects of heating the wall for 10 seconds on the flowing water for the remaining 50 seconds of the simulation. How can I do this?
Thank You Very Much
suppose that I have a channel through which water flows. at first, the top and bottom walls of the channel are heated by a temperature of for instance 400 K. I want to run this case for, "for example" 60 seconds but, "for example" for first 10 seconds of the simulation, the boundary condition is a constant temperature heated wall (of course my real boundary condition for this 10 seconds should be run as transient not stationary) and for the 50 seconds of the remaining simulation the heated wall boundary condition is off and the boundary condition is changed to no slip wall. I want to do this to see the effects of heating the wall for 10 seconds on the flowing water for the remaining 50 seconds of the simulation. How can I do this?
Thank You Very Much
2 Replies Last Post Nov 1, 2015, 7:25 a.m. EST
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Hi
I believe that is straight forward, and if I understand you well, you have a boundary with a heat source depending on the time (something like a q(t[s])[W/m^2]) and you have fluid flow => "no-"slip conditions.
But for me these are BC's for different physics, the "no-slip" condition remains for the SPF Fluid flow if you have or not any heat source, the only thing is that you should modulate your heat flux by a step function to turn it off, (if possible smoothly by a "Definition - Function - step" rather than by a Boolean function, as continuous derivable functions always behave better with the time stepping solvers.
Or have I missed something ?
--
Good luck
Ivar
I believe that is straight forward, and if I understand you well, you have a boundary with a heat source depending on the time (something like a q(t[s])[W/m^2]) and you have fluid flow => "no-"slip conditions.
But for me these are BC's for different physics, the "no-slip" condition remains for the SPF Fluid flow if you have or not any heat source, the only thing is that you should modulate your heat flux by a step function to turn it off, (if possible smoothly by a "Definition - Function - step" rather than by a Boolean function, as continuous derivable functions always behave better with the time stepping solvers.
Or have I missed something ?
--
Good luck
Ivar
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Hi Ivar,
as a matter of fact the heated wall was an example. In my real case, I want to apply electric field to the channel walls for a short period and then deactivate the electric field and see what effects do the applied electric field have on the flow field for the rest of the simulation. whit this new explanation should I do the same way you told or not?
thank you very much Ivar
as a matter of fact the heated wall was an example. In my real case, I want to apply electric field to the channel walls for a short period and then deactivate the electric field and see what effects do the applied electric field have on the flow field for the rest of the simulation. whit this new explanation should I do the same way you told or not?
thank you very much Ivar