2 Way FSI Problem
 

Hi all,

I have a problem with building a 2-Way FSI case. First of all, i would like to use both heat transfer and mesh motion in the same run. I am using CFX for fluid solver and ANSYS for structural side. I am preparing a mechanical ".inp" file for Multifield Analysis. Mechanical input file is built by multiphysics, i mean it can solve both thermal and structural. The element type is Solid226. I prepared the inp file in workbench and embeded a command to change the element type. Because in workbench, Transient Structural analysis system give aoutomatically Solid186 or similar..

Now, the case is running, i dont have a problem with it. But the problem is in this case, only mesh deformation is transfering between CFX and ANSYS. But i need thermal stresses.

CFX needs an "interface" boundary domain between solid and fluid domains to be able to run a heat transfer problem. But on the other hand, for FSI problem, i need a "wall" boundary domain to be able to transfer the mesh motion(especially) and heat transfer. For heat transfer i am trying to send to Ansys "Wall Heat Flow", and receiving "Temperature" from Ansys. and for mesh motion;from CFX, i am trying to send "Total Force" to Ansys and receiving from Ansys "Total Mesh Displacement". But as it seems that only mesh motion transfer works..!



Also i am receiving a note from Ansys output:


************************************************** ***************************
*** NOTE *** CP = 11106.921 TIME= 17:49:12
New Solution Control Option is only valid for a single field structural
or thermal analysis. The SOLCONTROL,ON command has been de-activated.
************************************************** ***************************


But at the same run, i can see this also in Ansys run:
At the bottom line, it says about HT Flow Convergence :s by the way thermal dofs are ON! what does it mean??? but why i cannot see any temp in the solid body!

************************************************** ************************
L O A D S T E P O P T I O N S

LOAD STEP NUMBER. . . . . . . . . . . . . . . . 29
TIME AT END OF THE LOAD STEP. . . . . . . . . . 0.29000E-02
NUMBER OF SUBSTEPS. . . . . . . . . . . . . . . 1
MAXIMUM NUMBER OF EQUILIBRIUM ITERATIONS. . . . 25
STEP CHANGE BOUNDARY CONDITIONS . . . . . . . . YES
TRANSIENT (INERTIA) EFFECTS
STRUCTURAL DOFS. . . . . . . . . . . . . . . ON
THERMAL DOFS . . . . . . . . . . . . . . . . ON
TRANSIENT INTEGRATION PARAMETERS
GAMMA. . . . . . . . . . . . . . . . . . . . 0.10000
ALPHA. . . . . . . . . . . . . . . . . . . . 0.30250
DELTA. . . . . . . . . . . . . . . . . . . . 0.60000
USING HHT TIME INTEGRATION
ALPHAF . . . . . . . . . . . . . . . . . . . 0.10000
ALPHAM . . . . . . . . . . . . . . . . . . . 0.0000
THETA. . . . . . . . . . . . . . . . . . . . 0.50000
OSCILLATION LIMIT CRITERION. . . . . . . . . 0.50000
TOLERANCE. . . . . . . . . . . . . . . . . . 0.20000
TERMINATE ANALYSIS IF NOT CONVERGED . . . . . .YES (EXIT)
CONVERGENCE CONTROLS. . . . . . . . . . . . . .USE DEFAULTS
PRINT OUTPUT CONTROLS . . . . . . . . . . . . .NO PRINTOUT
DATABASE OUTPUT CONTROLS
ITEM FREQUENCY COMPONENT
ALL NONE
NSOL ALL
RSOL ALL
NLOA ALL
STRS ALL
EPEL ALL
EPPL ALL
V ALL
A ALL

FORCE CONVERGENCE VALUE = 0.2163E-12 CRITERION= 0.1752
HT FLOW CONVERGENCE VALUE= 0.8834E-14 CRITERION= 0.1000E-08
EQUIL ITER 1 COMPLETED. NEW TRIANG MATRIX. MAX DOF INC= -0.3626E-17
FORCE CONVERGENCE VALUE = 0.9861E-13 CRITERION= 0.1752 <<< CONVERGED
HT FLOW CONVERGENCE VALUE= 0.8506E-14 CRITERION= 0.1000E-08 <<< CONVERGED
************************************************** *******************************


What should i do for both mesh motion transfer and heat transfer in a FSI problem?

In CFX you should have a wall boundary condition, with the mesh motion settings set to send forces and receive diplacements, and the heat transfer settings set to send heat flows and receive temperature. The CFX setup should not include any solid domains that are included in ANSYS (i.e. you cannot solve a CHT case in CFX and send the interface thermal data to ANSYS when using 2-way FSI), so you shouldn't have any interface boundaries in CFX that need to send data to ANSYS.

Actually, i am also trying to solve heat transfer in Ansys side. i did exactly what you said. but problem is ansys didnt solve the heat transfer...

Salam Ali bas,

I have a doubt in FSI related to ANSYS MFX FSI b/w CFX and structural.

I tried to couple wit ANSYS Structure and CFX but I have some problems in hand. I am working of FSI of flow through flexible tube.

Can u tel me, how did u transfer ansys structural file to workbench...?

I have no problem wit Fluid, but for structure, I tried to mesh in gambit and bring it to ansys classic, applied boundary conditions. but stuck up wit writing input file. (.inp). I tried using saveas option and created it and then linked wit CFX, but during solution its not recognising.

Can u tel me what is the procedure in transfering mesh from clasic to workbench and method of creating inp file in classic.

Hi Smak,

First of all, i use only workbench modules for fsi cases. it is a little bit different in classic mode. to export a input file in classic, in file tab there may be write input file tab. and in in workbench, ,n the transient or static structural analysis, in the tools tab there is "write input file" you can prepare all your case in workbench and get input file then use it inside the cfx module...

Problem in FSI using CFX-ANSYS
 

the problem of FSI using CFX and ANSYS classic is solved.

But there is another hurdle popping up.

The CFX solves in cylindrical coordinate system, when the results are viewed in CFX post for structure, its showing in cartesian system, May i know is there any way of solving this problem.

Also I tried to see the structural results in ANSYS classic, but there also its in cartesian only, when I tried to view in cylindrical also,, the results are shown in cartesian only.

How did you generate the ansys .inp file for CFX from Ansys Classic?

My input file generated from Workbench is very different from that one of Classical generates. When I try to run the coupled analysis from CFX, it says that:

"No boundary condition that is compatible with the following data transfer definition could be identified: "

However, in Ansys Classic, before I generate the .inp file, I set the FSIN flag....

Thanks in advance

Problem in transfering temperature data between two domains
 

Hello every body

I am also modeling 2-way FSI with Workbench version 13.
i want to transfer temperature data from CFX to Ansys, so i need to define non adibatic boundary condition in CFX for walls to active heat transfer between inner flow and the CFD walls, i did that and i selected heta transfer coefficient, so it asks two things: heat transfer coefficient and outside temperature , now my problem is setting the outside temperature because outside temperature is an unknow and actually the temperature of inner flow which we have to define. Attachment 10366

Hello Guys,

I am doing stress analysis for a compressor blade.

I have done flow analysis in CFX and have result file. Now wants to do stress analysis in Ansys classic. How can i import pressure loading through a CGX result file?

I know it is easy to do i workbench but dur to some conditions i have to import in ansys classic. Pls let me know how can it possible?

Regards,

dear friend
I am doing two way fsi. My structural model has a fixed temperature. I have to send heat to the fluid domain and receive heat from fluid to solid.
similarly, to send forces and displacements.
please clarify the way of setting in the ansys workbench which has been attached for your reference.

Thank you so much for your timely advice

Regards

Govind

how to rectify this
 

Run mode: serial run

Host computer: HTML2-PC (PID:4180)
Job started: Thu Dec 12 16:57:45 2013

Connecting to the following master process:
Host Name : HTML2-PC
Port Number : 60288

+--------------------------------------------------------------------+
| ERROR #002100049 has occurred in subroutine CPLG_SetupBcp. |
| Message: |
| No boundary condition that is compatible with the following data |
| transfer definition could be identified: |
| |
| Sending process : ANSYS |
| Sending region : 1 |
| Sending variable : DISP |
| Receiving process : CFX |
| Receiving region : interface1 |
| Receiving variable: Total Mesh Displacement |
| |
| Please review the ANSYS CFX boundary condition and external data |
| transfer definitions. |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Failed in solver setup synchronization point. |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| CFX encountered the error: |
| -11000. |
| |
| |
| |
| |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Stopped in routine SYNP_SOLVERSETUP |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| An error has occurred in cfx5solve: |
| |
| The ANSYS CFX solver exited with return code 1. No results file |
| has been created. |
+--------------------------------------------------------------------+

End of solution stage.

+--------------------------------------------------------------------+
| An error has occurred in cfx5solve: |
| |
| ANSYS Solver terminated with return code 3840 |
+--------------------------------------------------------------------+


+--------------------------------------------------------------------+
| The results from this run of the ANSYS solver have been written to |
| C:\Users\html2\Desktop\abcd_pending_tasks\dp0_CFX_ Solution\Fluid |
| Flow CFX_008.ansys |
+--------------------------------------------------------------------+


This run of the ANSYS CFX Solver has finished.

2 Way FSI runs only with maximum 2 cores in ANSYS v14.5
 

Hi all,

I have a problem with my total solution time,

I am modelling a flexible artery in Ansys v14.5 by an eight core system (3.4 GHz) with 8 GB ram, with 2300 elements for solid part and 94000 elements for fluid part and laminar flow, my total solution time is about 2 days, my first question is that is it normal? And my second question is when I hold mouse cursor on Ansys mechanical APDL Batch running window it shows that the solver is running with 2 cores, I changed every solver settings to 8 cores, but it does not help, what should I do?

Hope to see a response.

Many thanks in advance:)

Hi mrkmrk,

I think, run time is not proper. But are you sure the problem is about ANSYS FEA? or the problem is on the CFD side? First of all, you need to check where the problem is.

I think, your CFD time increment is very small since ANSYS tries to get every increment for stagger loops.. IF Your CFD analysis is laminar flow, you should check time increment first, then decrease the stagger loops.

Hope this helps

Ali

Hi,
 

i am doing CFD analysis of Turbocharger Turbine for Producer gas Engines, can anybody please give me the hints regarding about Turbine Performance characters like shaft power, then power coefficient please.
please mail me on naveenmyself@ymail.com:)

Hi prashant gour,

Did you define FSI surfaces for both ansys and cfx side?

I think, cfx cannot transfer displacement data to ansys in regard to below error;

""No boundary condition that is compatible with the following data |
| transfer definition could be identified:""

Thanks,
Ali

Hi Ali,
Thanks for your attention; I really appreciate your help.


The time step in my simulation is 0.01 and the total time (end time) is 8 sec. The convergence in any part of solid or fluid is very quick, whereas (I think) the problem is the interface convergence. In ‘solver control external coupling’ section,’ the relaxation factor’ is set to 0.5 (more values lead to divergence) while ‘the convergence target’ is set to 0.001. Is there any way to run the Mechanical APDL with more than 2 cores?"
Thanks in advance.:)

I am not sure if you really gain speed up when running in parallel with 2300 elements for solid part and 94000 elements for fluid part because the information transfer for the parallel run is more than the actual element number per core. The transfer is eating up the speedup. Depending on total time/timestep and number of stagger iterations per timestep 2 days sounds not that wrong. Anyways, you should definitely run not more cores then the system has in total (means 8 cores = 6 cfd + 2 csm instead of 8+8 or 8+2)

Hi mrkmrk,

You can increase Ansys core number by pop-up window on cfx side. The window i say is all the settings you are doing. Look more close to tabs. I could not remember exact place now.

Thanks,
Ali

mrkmrk,

For data transfer by FSI interfaces propoerly, you may need to have similar mesh size on both size. I recommend this also.

Thanks

Hi Ali, Matthias

Thank you for your useful responses,:)

The problem was solved,:)

Good luck.