Online CFD Course - Recent Threads

An error about residual of Mass is Not A Number: the solver has been stopped application

Huibo — Wed, 13 Mar 2024 15:01:39 GMT

Dear,

First I use the K-w flow model stimulate my model, it could work. But I would like to test another model (S-BSL-EARSM), it didn't work. It was showing :residual of Mass is Not A Number: the solver has been stopped
application.

Could you please give me some suggestion about this issue? I have no idea about this.

Looking forward to your reply.

Best regards,

Huibo

CFD online course 2023-2024

nhatminh — Wed, 31 Jan 2024 10:19:06 GMT

Hello,

my name is Minh Tran, and I have registered for the CFD course for the 2023-2024 session. I have received the confirmation email, but as of now, I haven't received instructions for the second step, which involves installing the CFD software.

I wanted to inquire whether the new course has commenced, and if not, could you please provide an estimate of when the instructions for the next steps will be sent?

I appreciate your assistance in this matter and look forward to your response.

Thank you and best regards,

Minh Tran

Size of the geometry different from what is shown in the demo video

Colinda — Mon, 18 Dec 2023 08:03:27 GMT

I was following the challenge from module 2 and it seems that the geometry (*.stl) that is provided for the elbow duct is half the size of the one shown in the demo video. This becomes evident when the mesh is generated; in order to get the same mesh, I need to specify an Initial cell size = 0.004 rather than 0.008 as shown in the video.

Lectures availability

Marco Ado — Mon, 13 Mar 2023 13:47:47 GMT

Hi,

I've noticed that it is no more possible to watch the recording of the lectures. Is it possible to unlock them for a few days? I would like to check for some information.

Thank you!

Pipe with varying cross-section

Commodaro — Mon, 06 Feb 2023 11:08:18 GMT

Hi,

Question 1

in instructions for Challenge 7, we have

Initial Solution: Vz=6 m/s

Boundary Condition - inlet: Vz=23 m/s

Should't they be equal to 23m/s ?

Question 2

Boundary Conditions - Outlet: averaged static pressure imposed.

Should we specify it as "Cartesian - Static pressure imposed" or as "Cylindrical - Static pressure imposed" (we used cylindrical for the Inlet)?

I see in the demo video that Cartesian is used.

thanks

Stefano

Pipe with varying cross-section: change of tables in simulation context

Konra — Tue, 31 Jan 2023 19:44:38 GMT

Hallo,
ich habe seit der letzten Challenge das Problem, dass sich die Tabelle im Simulationskontext nicht ändern lässt. Egal wie oft ich die Simulation neu durchlaufen lasse, ich kann mir nicht den Totaldruck und y+ anzeigen lassen. Auch im Convergence monitor kann ich unter Physical quantities nur noch Lift, Drag und Moment auswhälen. Massenstrom ist nicht mehr vorhanden. Unten in der Tabelle werden verscheidene Werte angezeigt, aber nicht der Totaldruck und y+, wie ich es im Simulations output eingestellt habe.

So kann ich die Challenge leider nicht weiterbearbeiten.

Calculation change in lift and drag.

AnasY — Tue, 24 Jan 2023 12:10:23 GMT

Hello,

In the questionnaire the formula to calculate the change in lift (analogical to drag) is given as followed: (lift_refined - lift_unrefined) / lift_unrefined. As the answers to choose from are given in percentage, am i correct in converting the result from the formula to percentage by moving two decimal places of the result to the right ?

Best regards.

M_Mesh Setup 1 Error: some process did not pass initialization

Larsne — Sat, 21 Jan 2023 12:49:15 GMT

Hallo, in Module 4 bekomme ich den oben genannten Fehlercode.

Tipps wie das verändern des Seed Points, komplett von neu anfangen oder den Haken bei parallel in den controll settings wegmachen helfen leider auch nicht. Habe mich komplett an die Einstellungen der Fallbeschreibung gehalten.

Hat jemand Tipps? Vielen Dank schonmal.

Error : Storage error, see vlog and contact developper

Philip Br — Mon, 16 Jan 2023 13:40:50 GMT

Hi,

I've got an error, which occures generally, not specific to a certain challenge...

After starting the mesh generation, everything is working fine, but instead of finishing the generation, a error message pops up:

This also happens in Projects, where the mesh was already generated and I tried to run a simulation.

I already tried reinstalling OMNIS and the Debug verbosity log doesn't log anything useful.

If anybody could tell me where to find the vlog or what this error message is referring to, I would be really grateful.

Kind regards Philip

The simulation has finished but the convergence criterion cannot be reached.

LV987 — Sun, 15 Jan 2023 18:17:50 GMT

What does this error mean?

Problem with starting the Simulation

NicoBu — Wed, 11 Jan 2023 21:28:46 GMT

Hi,

I always get the following Problem while trying to start the simulation.

Cannot start the computation: Simulation 1 - Problem(s) in Domain 1: -> The selected mesh is not compatible with the current active design: Choice 1. Please, select another one.

How can I fix this?

Kind regards

Result Analysis not showing Surface of cutting Plane => no Results visible

VitusR — Tue, 10 Jan 2023 07:54:01 GMT

Hi,

when doing the result analysis I have the following Problem:
After clicking on the Cutting Plane, it creates a cutting Plane in a random direction and shows the surface it is cutting

However, as soon as I click on "Y" to set the Plane normal to the Y axis, this monocoloured orange surface disappears

Nothing else was changed, except for pressing the Y. I can#t find any option to get the cut surface back, so I cant visualize my Results.
When selecting the cutting Plane and creating a Mach-Probe it does give me the scale, but since theres no surface to display it on I can't see any other data.

Any ideas on what could solve this?

Mesh generation fails (some process did not pass initialization)

VitusR — Mon, 09 Jan 2023 08:49:35 GMT

Hi, when following along the Module 3 I get following Error Message when trying to start the Mesh generation:

M_Mesh Setup Full Error: some process did not pass initialization

This happens using the "Full" Choice, with the Seedpoint beeing inside the Geometry and underneath (-z) the Symmetry Plane.

Can one of you tell me what I did wrong? Thanks in Advance!

Simulation settings Standard or Advanced

SJL5 — Wed, 04 Jan 2023 18:00:24 GMT

Hallo zusammen,

wie stellt man die Simulationseinstellungen auf den Modus Standard und die Domaineinstellung auf Advanced? Bei mir springt die Simulationseinstellung auch auf Advanced, wenn ich die Domain auf Advanced schalte.

Viele Grüße

Turbulent Inflow Elbow duct

NmiT — Thu, 29 Dec 2022 17:04:10 GMT

Hello,

If been following along to the video of class 3 and applied all the variables provided in the presentation. Despite applying an Euler BC on the wall, my simulation doesn't show a uniform velocity distribution. Also my shock seems to be more of the oblique type, as there is still a significant amount of supersonic flow behind the kink. This also causes my simulation to take way more iterations than options provided in the test.

Is there something in the video that I missed that might cause this kind of flow?

Best regards

Tim

Elbow duct

SimonGohle — Wed, 21 Dec 2022 16:29:55 GMT

I wonder if in the formulation of the excersie 4 the maxmial outlet velocity in x direction is at the old outlet for the extendet pipe?

Probe creation

carll — Tue, 20 Dec 2022 14:21:32 GMT

Hi,

I was following along with the video tutorial of Module 3 and up to the result analysis step, everything worked well.

But when I try to add a probe to the cutting plane I don't get values for the Mach number.

Is there a common mistake I made?

Or should I come into the live Q&A?

Thank you in advance.

Epsilon in initial solution and boundary condition

MaxiWei — Tue, 20 Dec 2022 06:51:31 GMT

Hi all,

is it correct that the value of epsilon change with the factor 10 between the initital soluttion and the boundary conditions?

Or is only the value of 0.7547 m2 /s3 correct? I think it's a typing error, but I just want to make sure. :)

Thank you very much!

Best regards

Max

CFD Course _ ERROR: residual of Mass is Not A Number: the solver has been stopped

NicoBu — Mon, 19 Dec 2022 22:44:23 GMT

Hi,

I always get the following Problem while simulating the half body with a CFL-Number of 3...

<img src="qrc:/warning"/> The simulation Simulation Half_CFL3 has failed: some NaN have been detected during the computation. ERROR: residual of Mass is Not A Number: the solver has been stopped

How can I fix this?

Kind regards

Converegence Monitor & Work units

LukasOde — Mon, 19 Dec 2022 17:47:26 GMT

Hello together,

is there a way to refresh the convergence monitor? Sometimes it get stucked and none of changes are displayed. For example I can’t zoom/move the curves, change the axis or selected Simulations.

The second question is about the work units. Is it correct that they have decimal places? I ticked the box foor latest value and get values like .8624. In my understanding it’s similar to the iterations.

Best regards,

Lukas

No Simulation context available

MaxiWei — Mon, 19 Dec 2022 07:23:23 GMT

Hi all,

I have the problem, that there is no simulation context I can select to simulate the projetct.

How could this happen and how can I fix this problem to complete the simulation of the 2nd challenge?

Tank you very much!

Best regards

Max

Problems with the Data; can not open Elbow duct

DilekY — Sun, 18 Dec 2022 21:35:17 GMT

Hello,

i cant open the elbow file. I get this message. Unfortunately, I cant finish this challenge. Can you extend the deadline? And how can I solve this Problem?

Unable start software.

SURYA45 — Fri, 16 Dec 2022 23:00:00 GMT

Hello Everyone,

my software had some problems. I did challenge 1 without a problem but now I can't open my software. Please check below Image.

Thank you.

Creating vector fields doesn´t work

Samjon — Thu, 15 Dec 2022 22:14:46 GMT

When I want to create a vector field on a cutting plane or any other, it is only creating a field of dots without any vectors, though the field's statics are showing velocities above 0 m/s.

Result analysis is running and enlarging or fitting the vectors doesn't help.

Is there any way to fix this?

Error in CFD online course Elbow duct.

Rishi Shenoy — Wed, 14 Dec 2022 19:53:20 GMT

Im using Omnis 5.2 software, as i simulate the elbow challenge im facing the error

<img src="qrc:/warning"/> The simulation Simulation 1 has finished but the convergence criterion cannot be reached. Check your simulation settings and residuals.

and i tried many times changing the CFL number also still im facing the error and i couldn't complete the tast.