OpenLabs - Recent Threads

RE: Unsteady inlet boundary condition with OpenLabs

Dianliang — Fri, 25 Apr 2025 08:53:23 GMT

Did you log in the support portal? The first return of the search should be the answer.

Alternatively, you can go to Product Manuals -> Silicon-Package-Board Co-Design -> Computational Fluid Dynamics -> Fidelity 2024.2 -> Setting up a simulation -> Optional models -> OpenLabs -> OpenLabs language -> Implicit and discrete expressions

Unsteady inlet boundary condition with OpenLabs

sriluta — Wed, 15 Feb 2023 11:30:41 GMT

Hey, I have at my inlet three Boundary conditions that changes with time and the azimuth angle. Arctg (Vt/Vz), Absolute total pressure and the absolute temperature. In the Inlet of my domain, I import the profiles, that changes with the azimuth angle. Now I want to change these profiles with the time too and I need to use OpenLabs for. In the tutotorial of OpenLabs I saw a expression with a sine function ( tutorial 2: customized unsteady Inlet boundary condition), but I don't like to use that. Is it possible to use an array of values ?

For example my time step is 0.000011s. At an azimuth angle of 0 degree I have a total pressure of 1 Bar and the time is 0. At an azimuth angle of 90 degree a have a total pressure of 2 bar and the time is 0.000011s. At an azimuth angle of 180 degree I have a total pressure of 3 bar and the time is 0.000022s and so on, is that possible ? I don't like to use a function here for.

Iam simulating a stator..

greetings Hussein

RE: Unsteady inlet boundary condition with OpenLabs

WS202504245114 — Fri, 25 Apr 2025 02:50:33 GMT

I couldn't find any information related to "discrete expression" on support.cadence.com.

RE: Unsteady inlet boundary condition with OpenLabs

sriluta — Wed, 14 Jun 2023 11:01:34 GMT

Hey, thx for your response. I use now the functions of the fourier series, as functions of the time and the azimuth angle :), iam using openLabs in Omnis 5.2

RE: Unsteady inlet boundary condition with OpenLabs

Dianliang — Fri, 02 Jun 2023 13:00:41 GMT

Just to complete, you can search discrete expression on support.cadence.com to find the relevant documentation (Implicit and discrete expressions) for Fidelity or Fine Open.

RE: Unsteady inlet boundary condition with OpenLabs

Colinda — Thu, 01 Jun 2023 18:40:38 GMT

Hi Hussein,

You could use a discrete expression in OpenLabs to define the total pressure and total temperature as a function of time and the azimuthal angle. Are you using OpenLabs in Fidelity or Fine Open? Which version are you using?

Best regards,
Colinda

RE: Problems with openLabs

sriluta — Thu, 06 Apr 2023 16:19:24 GMT

thx for your response, ah okay not only the boundary condition needs to be named, the boundary too. I want to modify the absolute total pressure and absolut total temperature at the inlet too, therefore i will use the name of the boundary conditions and the boundary inlet too, thx

Problems with openLabs

sriluta — Mon, 03 Apr 2023 10:38:59 GMT

Hey,

iam using OpenLabs because my inlet boundary conditions change with the time and the azimuth angle in the unsteady Simulation. So OpenLabs works with SI Units. In the first time, I defined the pressure in bar ( since didn't know that OpenLabs works with SI Units and there the pressure is defined in pascal ). So with the following function implemented in OpenLabs for the absolut total pressure I didn't got Problems:

3.853 + (-0.9863)*cos(tCoord*1.966 + 2*PI*Time/timePeriod) + 0.08183*sin(tCoord*1.966+ 2*PI*Time/timePeriod) + (-0.2735)*cos(tCoord*3.932+ 2*PI*Time/timePeriod) + 0.6356*sin(tCoord*3.932+ 2*PI*Time/timePeriod) + 0.588*cos(tCoord*5.88 + 2*PI*Time/timePeriod) + (-0.1489)*sin(tCoord*5.88 + 2*PI*Time/timePeriod) + (-0.07768)*cos(tCoord*7.864 + 2*PI*Time/timePeriod) + (-0.2232)*sin(tCoord*7.864 + 2*PI*Time/timePeriod) + (-0.3242)*cos(tCoord*9.83 + 2*PI*Time/timePeriod) + 0.01536*sin(tCoord*9.83 + 2*PI*Time/timePeriod) + 0.1678*cos(tCoord*11.796+ 2*PI*Time/timePeriod) + 0.2214*sin(tCoord*11.796 + 2*PI*Time/timePeriod) + 0.1408*cos(tCoord*13.762 + 2*PI*Time/timePeriod) + (-0.0754)*sin(tCoord*13.762+ 2*PI*Time/timePeriod) + (-0.1216)*cos(tCoord*15.728 + 2*PI*Time/timePeriod) + (-0.1922)*sin(tCoord*15.728 + 2*PI*Time/timePeriod)

when I found out that OpenLabs works in SI units, I converted the sizes from bar to pascal and created the new following function:

390101.438+ (−99956.492)*cos(1.963*tCoord + 2*PI*Time/timePeriod)+ 9062.116*sin(1.963*tCoord + 2*PI*Time/timePeriod)+ (−26626.657)*cos(3.927*tCoord + 2*PI*Time/timePeriod)+63969.754*sin(3.927*tCoord + 2*PI*Time/timePeriod)+57284.906*cos(5.890*tCoord + 2*PI*Time/timePeriod) + (−15828.864)*sin(5.890*tCoord + 2*PI*Time/timePeriod) + (−8525.752)*cos(7.854*tCoord + 2*PI*Time/timePeriod) + (−21014.003)*sin(7.854*tCoord + 2*PI*Time/timePeriod) + (−30331.247)*cos(9.817*tCoord + 2*PI*Time/timePeriod)+2857.566*sin(9.817*tCoord + 2*PI*Time/timePeriod)+15956.411*cos(11.781*tCoord + 2*PI*Time/timePeriod)+19562.181*sin(11.781*tCoord + 2*PI*Time/timePeriod)+11641.815*cos(13.744*tCoord + 2*PI*Time/timePeriod) + (−6956.443)*sin(13.744*tCoord + 2*PI*Time/timePeriod) + (−10933.721)*cos(15.708*tCoord + 2*PI*Time/timePeriod) + (−14834.89)*sin(15.708*tCoord + 2*PI*Time/timePeriod).

If I click in OpenLabs at validate labs everything is fine, if I start the Simulation, the Simulation stops from beginning and say there is a problem with OpenLabs. I also defined the functions for the absolut Total Temperature and arctg( Vt/Vz) and there are no Problems but just with the pressure. Now I dont know what to do,

greetings [emoticon:c4563cd7d5574777a71c318021cbbcc8]

RE: Problems with openLabs

Dianliang — Thu, 06 Apr 2023 08:56:29 GMT

You must provide the information of the boundary that will be customized. Otherwise, OpenLabs cannot know which boundary needs to be changed.

The "Inlet" in FineOpen tutorial is the name of the boundary.

RE: Problems with openLabs

sriluta — Wed, 05 Apr 2023 10:02:15 GMT

ah good to know thx, one last thing would be, in the analysis context I can see the name of the boundary condition I want to modify. For example: "absoluteTotalTemperature", to write in OpenLabs the command ExistingBc, so in the tutorial of fineOpen there is written Inlet too, is that necessary ? ->ExistingBC: "absoluteTotalPressure", Inlet

otherwise how can I keep the memory of the simulation smaller or reduce it. Maybe under Simulation/Control -> output Solution every ... time Steps ?

RE: Problems with openLabs

Dianliang — Tue, 04 Apr 2023 20:31:21 GMT

Hi,

OMNIS allows long expression. The problem is not due to the expression but something else. Next time, if you encounter the same issue, you can check the log file located in the folder _openlabs under the simulation directory.

Regards,

Dianliang

RE: Problems with openLabs

sriluta — Tue, 04 Apr 2023 15:07:48 GMT

Hey,

I really dont get it. I have now restarted the simulation and again taken the function defined in Pascal and there are no more problems. I can even increase the number of terms up to 29 without problems, the only thing that has changed from yesterday to today, the restart of the laptop :D. Yesterday, however, the method mentioned above was the only possible one, maybe the whole thing is due to the fact that the functions are so long, however, it still does not make sense....

RE: Problems with openLabs

Colinda — Tue, 04 Apr 2023 10:16:41 GMT

Hi,

We could not reproduce in Omnis 5.2.
Could you please send an email to academic-cfd@cadence.com for further investigation?

Best regards,

Colinda

RE: Problems with openLabs

sriluta — Mon, 03 Apr 2023 16:46:02 GMT

I am now made on an interesting context. When the sizes were given in bar and the coefficients were correspondingly small, there was no error message at all during the simulation. When the function in Pascal and coefficients and numbers became very large the simulation did not run. Therefore I have thought that it can be because of numbers which are possibly simply too large, but I do not understand why this should be so. For example, I could never exceed the limit of 15 terms, but now I have taken 20 terms. And individual values that are a little larger are reduced and multiplied by 1e1 as you will see in the functions. And now the simulation runs with 20 terms.
The following 1st function is unprocessed and the 2nd function is processed with 1e1 and does not cause any problems with the simulation:

1650.4065 + (-112.848)*cos(1.963*tCoord + 2*PI*Time/timePeriod) + (4.398)*sin(1.963*tCoord + 2*PI*Time/timePeriod) + (-34.2)*cos(3.927*tCoord + 2*PI*Time/timePeriod) + (80.262)*sin(3.927*tCoord + 2*PI*Time/timePeriod) + (69.031)*cos(5.890*tCoord + 2*PI*Time/timePeriod) + (-24.899)*sin(5.890*tCoord + 2*PI*Time/timePeriod) + (-15.064)*cos(7.854*tCoord + 2*PI*Time/timePeriod) + (-23.672)*sin(7.854*tCoord + 2*PI*Time/timePeriod) + (-27.692)*cos(9.817*tCoord + 2*PI*Time/timePeriod) + (6.149)*sin(9.817*tCoord + 2*PI*Time/timePeriod) + (15.507)*cos(11.781*tCoord + 2*PI*Time/timePeriod) + (18.800)*sin(11.781*tCoord + 2*PI*Time/timePeriod) + (12.292)*cos(13.744*tCoord + 2*PI*Time/timePeriod) + (-7.547)*sin(13.744*tCoord + 2*PI*Time/timePeriod) + (-11.297)*cos(15.708*tCoord + 2*PI*Time/timePeriod) + (-16.009)*sin(15.708*tCoord + 2*PI*Time/timePeriod) + (-7.647)*cos(17.671*tCoord + 2*PI*Time/timePeriod) + (12.403)*sin(17.671*tCoord + 2*PI*Time/timePeriod) + (8.697)*cos(19.635*tCoord + 2*PI*Time/timePeriod) + (7.403)*sin(19.635*tCoord + 2*PI*Time/timePeriod) + (5.674)*cos(21.598*tCoord + 2*PI*Time/timePeriod) + (-11.008)*sin(21.598*tCoord + 2*PI*Time/timePeriod) + (-8.233)*cos(23.562*tCoord + 2*PI*Time/timePeriod) + (-3.261)*sin(23.562*tCoord + 2*PI*Time/timePeriod) + (-3.985)*cos(25.525*tCoord + 2*PI*Time/timePeriod) + (8.205)*sin(25.525*tCoord + 2*PI*Time/timePeriod) + (7.937)*cos(27.489*tCoord + 2*PI*Time/timePeriod) + (1.267)*sin(27.489*tCoord + 2*PI*Time/timePeriod) + (0.605)*cos(29.452*tCoord + 2*PI*Time/timePeriod) + (-6.452)*sin(29.452*tCoord + 2*PI*Time/timePeriod) + (-6.257)*cos(31.416*tCoord + 2*PI*Time/timePeriod) + (0.000)*sin(31.416*tCoord + 2*PI*Time/timePeriod) + (0.471)*cos(33.379*tCoord + 2*PI*Time/timePeriod) + (5.023)*sin(33.379*tCoord + 2*PI*Time/timePeriod) + (4.801)*cos(35.343*tCoord + 2*PI*Time/timePeriod) + (-0.767)*sin(35.343*tCoord + 2*PI*Time/timePeriod) + (-1.866)*cos(37.306*tCoord + 2*PI*Time/timePeriod) + (-3.841)*sin(37.306*tCoord + 2*PI*Time/timePeriod) + (-2.964)*cos(39.270*tCoord + 2*PI*Time/timePeriod) + (1.174)*sin(39.270*tCoord + 2*PI*Time/timePeriod)

1650.4065 + (-11.2848*1e1)*cos(1.963*x) + (4.398)*sin(1.963*x) + (-3.42*1e1)*cos(3.927*x) + (8.0262*1e1)*sin(3.927*x) + (6.9031*1e1)*cos(5.890*x) + (-2.4899*1e1)*sin(5.890*x) + (-15.064)*cos(7.854*x) + (-2.3672*1e1)*sin(7.854*x) + (-2.7692*1e1)*cos(9.817*x) + (6.149)*sin(9.817*x) + (15.507)*cos(11.781*x) + (18.800)*sin(11.781*x) + (12.292)*cos(13.744*x) + (-7.547)*sin(13.744*x) + (-11.297)*cos(15.708*x) + (-16.009)*sin(15.708*x) + (-7.647)*cos(17.671*x) + (12.403)*sin(17.671*x) + (8.697)*cos(19.635*x) + (7.403)*sin(19.635*x) + (5.674)*cos(21.598*x) + (-11.008)*sin(21.598*x) + (-8.233)*cos(23.562*x) + (-3.261)*sin(23.562*x) + (-3.985)*cos(25.525*x) + (8.205)*sin(25.525*x) + (7.937)*cos(2.7489*1e1*x) + (1.267)*sin(2.7489*1e1*x) + (0.605)*cos(29.452*x) + (-6.452)*sin(2.9452*1e1*x) + (-6.257)*cos(3.1416*1e1*x) + (0.000)*sin(3.1416*1e1*x) + (0.471)*cos(3.3379*1e1*x) + (5.023)*sin(3.3379*1e1*x) + (4.801)*cos(35.343*x) + (-0.767)*sin(3.5343*1e1*x) + (-1.866)*cos(3.7306*1e1*x) + (-3.841)*sin(3.7306*1e1*x) + (-2.964)*cos(3.9270*1e1*x) + (1.174)*sin(3.9270*1e1*x)

You can see what I mean from the color markings. Don't be surprised, I replaced tCoord with x and removed + 2*PI*Time/timePeriod because I wanted to test something in Matlab.

RE: Problems with openLabs

sriluta — Mon, 03 Apr 2023 15:30:37 GMT

Hey, thx for your response. Yes, the . in the end is also removed. Iam working with Omnis 5.2 and the OS is windows 10. There are no line breaks, put the whole function in one line. So if I start the Simulation I get the following error:

"The Simulation Simulation 1 has been stopped: an error occurred during the computation. OpenLabs Error"

the log file:

- OpenLabs Module is activated

- OPENLABS ERROR: OpenLabs is active for block 0 but the library ..../domain_100000000055232.dll) does not exist, exciting . . .

- info : [NIMPI : : mpiAbort] OPENLABS ERROR.

So what I have now done to avoid the error message, is used the first expression which are defined in bar, put the whole function in mathematical brackets and multiplicate the function with *100.000, also: (3.853 + ...........))*100.000 and now I dont get an error anymore.

Another question would be is there a limit in the Number of characters in the function in OpenLabs ? So I if use up to 15 Terms for the function of the fourier series everything Is fine, if I want to use 20 terms and more, the simulation is stopped right at the beginning.

RE: Problems with openLabs

Colinda — Mon, 03 Apr 2023 14:45:10 GMT

The expression in Pascal is correct except that "." needs to be removed from the end of the line.

If that does not work, we need more information:

Which version are you using? Fidelity 2022.2?

On which OS version are you running?

If Linux: which gcc version?

Please confirm whether you are using line breaks and if so that they are used consistently? Or did you put all in one line?

What exactly is the error message? Is there more detail in the log?

Best regards,
Colinda

RE: Problems with openLabs

sriluta — Mon, 03 Apr 2023 12:26:08 GMT

ah okay, good to know thx

RE: Problems with openLabs

Andrew Beckett — Mon, 03 Apr 2023 12:17:54 GMT

Note from a moderator (can't answer the technical question because it's not my field) - the issue with this being caught as potential spam is because of the repeated text. Clearly it's not spam, but that's a common feature of spam, I'm afraid.

Andrew

RE: Problems with openLabs

sriluta — Mon, 03 Apr 2023 11:13:10 GMT

maybe I how to work with the pow command ? So If I want to transform the first function from bar to pascal in OpenLabs, I think I have to write it in this way:

pow(( 3.853 + (-0.9863)*cos(tCoord*1.966 + 2*PI*Time/timePeriod) + 0.08183*sin(tCoord*1.966+ 2*PI*Time/timePeriod) + (-0.2735)*cos(tCoord*3.932+ 2*PI*Time/timePeriod) + 0.6356*sin(tCoord*3.932+ 2*PI*Time/timePeriod) + 0.588*cos(tCoord*5.88 + 2*PI*Time/timePeriod) + (-0.1489)*sin(tCoord*5.88 + 2*PI*Time/timePeriod) + (-0.07768)*cos(tCoord*7.864 + 2*PI*Time/timePeriod) + (-0.2232)*sin(tCoord*7.864 + 2*PI*Time/timePeriod) + (-0.3242)*cos(tCoord*9.83 + 2*PI*Time/timePeriod) + 0.01536*sin(tCoord*9.83 + 2*PI*Time/timePeriod) + 0.1678*cos(tCoord*11.796+ 2*PI*Time/timePeriod) + 0.2214*sin(tCoord*11.796 + 2*PI*Time/timePeriod) + 0.1408*cos(tCoord*13.762 + 2*PI*Time/timePeriod) + (-0.0754)*sin(tCoord*13.762+ 2*PI*Time/timePeriod) + (-0.1216)*cos(tCoord*15.728 + 2*PI*Time/timePeriod) + (-0.1922)*sin(tCoord*15.728 + 2*PI*Time/timePeriod)),1e5) ?

RE: Cavitation with Thermodynamics table issue

JosephSmith — Thu, 26 Jan 2023 10:54:28 GMT

Hi Botond,

Thank you for the response and the advice. I will try them out.

Kind regards,
Joseph

Cavitation with Thermodynamics table issue

JosephSmith — Wed, 04 Jan 2023 15:54:01 GMT

Greetings,

I have been attempting to use thermodynamic tables to simulate cavitation within a turbopump. Water was the working fluid. However, I have been getting a run time error right at the beginning of the simulation – this is seen in the attached log file I copied.

[View:/cfs-file/__key/communityserver-discussions-components-files/125/3146.thermotable-error.txt:640:480]

I followed the parameter guidelines in the FINE Open user and theory guide when using the thermodynamic tables option (I first changed the iCavitation_ value to 2 then changed the rest of the parameters locally in the advanced Control variables tab). The initial solution was taken from a converged run without cavitation models. This initial solution worked with the Barotropic cavitation model but not with Thermodynamic tables.

I’m still in the process of troubleshooting possible ways of where the error lies. Not certain if its relevant to the error, but I did not understand what the user manual meant by using thermodynamics tables in the Physical configuration > Fluid model page, seen in attached image.

I would appreciate any assistance on the error or to what the manual referred to for the former.

Kind regards,

Joseph

RE: Cavitation with Thermodynamics table issue

BIPal — Thu, 26 Jan 2023 10:45:59 GMT

Hi Joseph,

Here's a few options you could try:

Try imposing velocity at the inlet and static pressure at the outlet. This is a more robust b.c. combination.
Try progressively reducing the CFL number to values as low as 0.1 and see if it helps.
Ensure that the range of quantities in the thermodynamic table you are using covers all of the expected thermodynamic states in the final solution. If it's not the case, there should be a warning in the log file that values from the tables are being clipped.

Let me know if the above helps.

Best regards,

Botond

RE: Cavitation with Thermodynamics table issue

JosephSmith — Tue, 24 Jan 2023 09:20:33 GMT

Hi Colinda,

I have tried adjusting expert parameters related to the Thermodynamic tables in the Control variables option to resolve my issue (such as turb_mutMuLimit_) but have had no luck unfortunately.

I am uncertain if my outlet boundary condition of Mass flow imposed with Pressure adaption and backflow control is possibly contributing to the issue at hand. I will also try using a lower amount of multigrid levels and see if there's any difference.

Besides the above, I am uncertain of what else I could try.

Kind regards,
Joseph

RE: Cavitation with Thermodynamics table issue

Colinda — Tue, 24 Jan 2023 08:46:21 GMT

Hi JosephSmith
Could you find the cause of trouble in your setup?

Best regards,
Colinda

RE: Cavitation with Thermodynamics table issue

JosephSmith — Wed, 18 Jan 2023 17:12:43 GMT

Hi Botond,

I see.

Alright, thanks for the confirmation. I will interrogate my cavitation setup again

regards,
Joseph