# Unaffected Results with Parameter **URL:** \ **Category:** General Discussion\ **Created:** [May 26, 2023, 1:39pm UTC](https://community.freefem.org/t/unaffected-results-with-parameter/2497 "2023-05-26T13:39:31Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![sumantkr](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/sumantkr/32/2681_2.png) [@sumantkr](https://community.freefem.org/u/sumantkr)\ **Post date:** [May 26, 2023, 1:39pm UTC](https://community.freefem.org/t/unaffected-results-with-parameter/2497/1 "2023-05-26T13:39:31Z")
Hello , I am surprised by the results of my 3d model. Its results remain unaffected for all values of parameters used in the model. [@prj@frederichecht] can anyone suggest/comment to resolve it? =================================== Also, an error is popping up for the plot: > "plot: Sorry no ps version for such type of plot 6 " ======================================= My code for cubic enclosure with bottom surface hot, upper surface cold, and insulated for all other surfaces in Cubic enclosures are as follows: [cubens.edp](https://community.freefem.org/uploads/short-url/avfLoKWQZxj7qgUJToCAsqOkiQE.edp) (3.2 KB) =================================== The mathematical model is as follows continuity equation > “\frac{\partial U}{\partial X} + \frac{\partial V}{\partial Y} + \frac{\partial W}{\partial Z} = 0” X-directional momentum equation: > “\begin{equation} \begin{split} \left( U\frac{\partial U}{\partial X} + V\frac{\partial U}{\partial Y} + W\frac{\partial U}{\partial Z} \right)& = - \frac{\partial P}{\partial X} + Pr\left( \frac{\partial^2 U}{\partial X^2} + \frac{\partial^2 U}{\partial Y^2} + \frac{\partial^2 U}{\partial Z^2} \right) \end{split} \end{equation}” Y-directional momentum eqn > “\begin{equation} \begin{split} \left( U\frac{\partial V}{\partial X} + V\frac{\partial V}{\partial Y} + W\frac{\partial V}{\partial Z} \right) =& -\frac{\partial P}{\partial Y} +Pr\left( \frac{\partial^2 V}{\partial X^2} + \frac{\partial^2 V}{\partial Y^2} + \frac{\partial^2 V}{\partial Z^2}\right) \\&- Ha^2 Pr V \end{split} \end{equation}” > “ \begin{equation} \begin{split} \left( U\frac{\partial W}{\partial X} + V\frac{\partial W}{\partial Y} + W\frac{\partial W}{\partial Z} \right) =& -\frac{\rho\_{f}}{\rho\_{nf}} \frac{\partial P}{\partial Z} + Pr\left( \frac{\partial^2 W}{\partial X^2} + \frac{\partial^2 W}{\partial Y^2} + \frac{\partial^2 W}{\partial Z^2}\right)\\& +RaPr\theta - Ha^2PrW \end{split} \end{equation}” > “ \begin{equation} U\frac{\partial \theta}{\partial X} + V\frac{\partial \theta}{\partial Y} + W\frac{\partial \theta}{\partial Z}= \left( \frac{\partial^2 \theta}{\partial X^2} + \frac{\partial^2 \theta}{\partial Y^2} + \frac{\partial^2 \theta}{\partial Z^2} \right) \end{equation}” ---
**Author:** ![marchywka](https://avatars.discourse-cdn.com/v4/letter/m/ee59a6/32.png) [@marchywka](https://community.freefem.org/u/marchywka)\ **Post date:** [May 27, 2023, 9:55am UTC](https://community.freefem.org/t/unaffected-results-with-parameter/2497/2 "2023-05-27T09:55:20Z")
I played with this for a while but could not get it t converge as written or with some modifications. I did question your boundary conditions however. If this is supposed to be energy and momentum, did you want to set U to zero at top and bottom? Also you have a cNewton factor on eqn labelled x momentum which does not look right. I can’t really tell much however since I can’t get it to converge… ---
**Author:** ![sumantkr](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/sumantkr/32/2681_2.png) [@sumantkr](https://community.freefem.org/u/sumantkr)\ **Post date:** [May 27, 2023, 10:41am UTC](https://community.freefem.org/t/unaffected-results-with-parameter/2497/3 "2023-05-27T10:41:39Z")
Hi @marchywka, this coupled equation ( momentum and energy) takes care of the continuity equation through the penalty FEM approach. Also, I have put velocity components zero at each surface due to the no-slip boundary conditions. In my case, it is converging but not affected by the value of the Rayleigh number. ![res3d](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/2X/f/f20faec49af65d729734a6213b4a4fe1dbce0c20.png) Also, changing boundary conditions show few noticeable changes in the iso-slice of temperature. Could you please give me a few relevant portals to learn and implement such problems? ---
**Author:** ![marchywka](https://avatars.discourse-cdn.com/v4/letter/m/ee59a6/32.png) [@marchywka](https://community.freefem.org/u/marchywka)\ **Post date:** [May 27, 2023, 12:23pm UTC](https://community.freefem.org/t/unaffected-results-with-parameter/2497/4 "2023-05-27T12:23:14Z")
Did you try plotting u\_z? Fluids isn’t really my thing but apparently the reynolds number involves the flow velocity and a transition to turbulent flow. If the veolocity is zero what will happen? You won’t really see much in any case until you approach a transition AFAICT. I guess you could try removing the boundariy conditions on u on the top or bottom or both and see what happens . Still puzzled why it won’t converge on my fresh clean install… ---
**Author:** ![sumantkr](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/sumantkr/32/2681_2.png) [@sumantkr](https://community.freefem.org/u/sumantkr)\ **Post date:** [May 27, 2023, 1:20pm UTC](https://community.freefem.org/t/unaffected-results-with-parameter/2497/5 "2023-05-27T13:20:49Z")
I have changed the boundary condition and parameter value, which works here: ========================= > real Ra= 10^4; Boundary conditions: > on(1,2,3,4,5,6, u1=0, u2=0, u3=0) > + on(1, T=sin(pi\*y))+ on(3, T=1) ; ======= Results======= # ![ra4d](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/2X/7/73a598d4a01effc79ce07a71b26f142b153936f4.png) However, could you please comment on identifying the orientation of a mesh as mentioned in [[3d labels questions](https://community.freefem.org/t/3d-labels-questions/2492)]? ---
**Author:** ![marchywka](https://avatars.discourse-cdn.com/v4/letter/m/ee59a6/32.png) [@marchywka](https://community.freefem.org/u/marchywka)\ **Post date:** [May 27, 2023, 11:01pm UTC](https://community.freefem.org/t/unaffected-results-with-parameter/2497/6 "2023-05-27T23:01:48Z")
It looks like I was just running out ot memory so I changed the elements to P1 instead of P2. If you plot e3, your boundary conditions on surfaces 5 and 6 create zero flow right? Reomve those and plot u3. With the reynolds number at 1e8 i looks a lot different lol. Not sure any of this is right but if you are modelling flow along z I’m not sure you cant to set flow to zero at both ends. I hacked up your code a lot there may be other changes … ---
**Author:** ![sumantkr](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/sumantkr/32/2681_2.png) [@sumantkr](https://community.freefem.org/u/sumantkr)\ **Post date:** [May 28, 2023, 2:36am UTC](https://community.freefem.org/t/unaffected-results-with-parameter/2497/7 "2023-05-28T02:36:28Z")
Thanks, @marchywka for your kind suggestions. Also, I’ll go through it thoroughly. I have one last doubt, could you please comment on identifying the direction of the axis for a mesh as mentioned in [[3d labels questions](https://community.freefem.org/t/3d-labels-questions/2492)]?