|
[Sponsors] |
July 12, 2019, 11:40 |
Boundary conditions for streamfunction
|
#1 |
Member
E
Join Date: Mar 2018
Posts: 77
Rep Power: 8 |
Hello to all,
I have written SIMPLE algorithm for 2D backwards facing step. My problem is to calculate streamfunction from Poisson equation. In the attached figure are the boundary conditions used correct? Thank you. Last edited by IbizaFR; July 12, 2019 at 11:42. Reason: corrections |
|
July 12, 2019, 13:21 |
|
#2 | |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,756
Rep Power: 71 |
Quote:
Yes, they are mathematically correct. You can use a more physically free outflow condition by setting d2 psi /dy2 =0 |
||
July 12, 2019, 15:30 |
|
#3 | |
Member
E
Join Date: Mar 2018
Posts: 77
Rep Power: 8 |
Quote:
With these boundary conditions i am solving a poisson equation but the resulting contours of calculated psi do not present the vortex near the bottom of step. |
||
July 12, 2019, 15:31 |
|
#4 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,756
Rep Power: 71 |
||
July 12, 2019, 15:37 |
|
#5 | |
Member
E
Join Date: Mar 2018
Posts: 77
Rep Power: 8 |
Quote:
The code for vorticity field is the same for the lid driven cavity in which the streamlines are compared good enough with other works. The same code for cavity I copied to facing step but it does not give correct results. Any help? |
||
July 12, 2019, 15:38 |
|
#6 | |
Member
E
Join Date: Mar 2018
Posts: 77
Rep Power: 8 |
Quote:
|
||
July 12, 2019, 16:22 |
|
#7 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,756
Rep Power: 71 |
||
July 12, 2019, 16:56 |
|
#8 |
Member
E
Join Date: Mar 2018
Posts: 77
Rep Power: 8 |
||
July 13, 2019, 14:10 |
|
#9 | |
Member
E
Join Date: Mar 2018
Posts: 77
Rep Power: 8 |
Quote:
Thank you. |
||
July 13, 2019, 14:11 |
|
#10 |
Member
E
Join Date: Mar 2018
Posts: 77
Rep Power: 8 |
Also the velocities for Re=333.
|
|
July 13, 2019, 15:09 |
|
#11 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,756
Rep Power: 71 |
From the figures the solutions seem obtained from a irrotational field. Check vorticity and convergence criteria
|
|
July 15, 2019, 13:41 |
|
#12 | |
Member
E
Join Date: Mar 2018
Posts: 77
Rep Power: 8 |
Quote:
Are they in a way correct? Thank you. |
||
July 15, 2019, 13:43 |
|
#13 |
Member
E
Join Date: Mar 2018
Posts: 77
Rep Power: 8 |
I also post the results for Re=167-200-250-300.
|
|
July 15, 2019, 15:58 |
|
#14 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,756
Rep Power: 71 |
The results show a better solution but something is still wrong. The recirculation region extends through the outflow. I suggest to extend the domain lenght and verify your reattachment lenght with the results in literature cited here
https://www.researchgate.net/publica...ical_procedure |
|
July 15, 2019, 16:42 |
|
#15 | |
Member
E
Join Date: Mar 2018
Posts: 77
Rep Power: 8 |
Quote:
|
||
July 15, 2019, 16:59 |
|
#16 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,756
Rep Power: 71 |
||
July 15, 2019, 17:09 |
|
#17 |
Member
E
Join Date: Mar 2018
Posts: 77
Rep Power: 8 |
||
July 15, 2019, 17:12 |
|
#18 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,756
Rep Power: 71 |
||
July 15, 2019, 17:20 |
|
#19 |
Senior Member
adrin
Join Date: Mar 2009
Posts: 115
Rep Power: 17 |
Curious, what was wrong with your poisson solver? If the code worked for the cavity flow it would mean your poisson solver is correct - except, of course, for the boundary condition.
Also, would you be able to share the algorithm you use for solving the vorticity transport equation? adrin |
|
July 15, 2019, 17:30 |
|
#20 | |
Member
E
Join Date: Mar 2018
Posts: 77
Rep Power: 8 |
Quote:
|
||
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
sliding mesh problem in CFX | Saima | CFX | 46 | September 11, 2021 08:38 |
Radiation in semi-transparent media with surface-to-surface model? | mpeppels | CFX | 11 | August 22, 2019 08:30 |
Basic Nozzle-Expander Design | karmavatar | CFX | 20 | March 20, 2016 09:44 |
GETVAR Error in Multiband Monte Carlo Radiation Simulation with Directional Source | silvan | CFX | 3 | June 16, 2014 10:49 |
Question about heat transfer coefficient setting for CFX | Anna Tian | CFX | 1 | June 16, 2013 07:28 |