Fine/Marine solver crash

https://entuedu-my.sharepoint.com/:i:/r/personal/paresh_halder_staff_main_ntu_edu_sg/Documents/Error%20message/screen%20shot.JPG?csf=1&web=1&e=reJiTw

I getting error massage for solver crash . Kindly help me regarding this issue.

@Halder, your link doesn't work (for me at least) and the external link caused your post to go into moderation. Rather than posting a link to a screenshot, use the Insert→Image/video/file in the posting box to add an image to your post (you can normally drag and drop the image into the post).

Andrew (not on this forum, but as a moderator of several others I allowed your post after the moderation appeal).

@Beckett sir, I am trying to upload a screenshot. But unable to do that. Kindly help regarding this issue.

I also have some doubts regarding the roughness calculation in the ship. I have simulated a full-scale KCS model, I used different size roughness. But I am not able to act above 500 micrometres. After that, I got the solver crashed. Is there any limitation for roughness size for full-scale ships? I am new in this area. Kindly advise me on how to resolve this issue. 

Hi,

I will ask developers about any limitation about the size of roughness but I am not aware of any limitation so far.

When you say "solver crashed", do you mean that the solver diverged? There is a difference between a crash (hard stop because of a defect) and a divergence (we see the residuals going up quite quickly).
I understand from your messages that you succeeded to get results for various simulations under 500micrometers but not above and it diverges above that value. Correct?

Best regards,

Benoit

@Mallol, yes the flow is diverged and indicated solver crash. In addition above 500 micrometer, the flow is diverged.

I have some doubt calculation regarding sinkage. I follow the KCS model but I am getting positive sinkage but most of literature  mentioned negative  value of sinkage. However, the origin is near stern side of the ship model. please guide me.    

Hi,

We quickly checked on a flat plate and we reproduced the behavior. If we increase the roughness a lot, the flow solver starts to diverge. The issue comes from the "leading edge" (equivalent of the front / bow for a ship). But the simulation converges much better with a lower Y+ (meaning decreasing the first cell size). It works well with Y+=20 and even better with Y+=1.

This is somehow unexpected, in particular since roughness was implemented for the wall function. But this is the workaround we can propose for the moment. This is not ideal for a ship at full scale since it will increase the number of cells, we are fully aware of that and we will take good note for the future improvements. An alternative could be to isolate a patch at the bow and decrease roughness just in this area to limit this behavior...

Best regards,

Benoit

Hi,

We quickly checked on a flat plate and we reproduced the behavior. If we increase the roughness a lot, the flow solver starts to diverge. The issue comes from the "leading edge" (equivalent of the front / bow for a ship). But the simulation converges much better with a lower Y+ (meaning decreasing the first cell size). It works well with Y+=20 and even better with Y+=1.

This is somehow unexpected, in particular since roughness was implemented for the wall function. But this is the workaround we can propose for the moment. This is not ideal for a ship at full scale since it will increase the number of cells, we are fully aware of that and we will take good note for the future improvements. An alternative could be to isolate a patch at the bow and decrease roughness just in this area to limit this behavior...

Best regards,

Benoit

Dear Mallol,

@Mallol Thank you for kind support. I try to implement as suggested and check roughness.

Please let me know how to access online fine/marine tutorial or could please allow me to access online learning material as well as tutorial.   

best regards, 

Paresh  

Dear Paresh,

Could you please give more detail on the license you are using?

In general access to support.cadence.com is provided together with the license. 
If you are a student and you are using the university license, you can ask your professor to request access to support.cadence.com.

If you have an individual student license, the Fine Marie documentation including tutorials are provided for download together with the installation files. 

Best regards,
Colinda

Dear Colinada,

The following details about the license 

Status: Academic 

License scheme: Perpetual license

I want access online learning. But not able to access. It is asking HOST id. I tried to system host id. But unable to access it. Please help me.

with best regards,

Paresh Halder

Dear Paresh Halder,

Could you pease send an email to academic-cfd@cadence.com confirming at which university and which faculty/department you are? 

If possible, please attach a copy of the license to allow me to find back the information more easily. If the perpetual license is without maintenance, the documentation, including the tutorials, was provided for download during the maintenance period.

Best regards,
Colinda

Dear Colinda,

I am writing regarding this unsteady CF post. I have completed the seakeeping simulation. After that, I moved this folder to another place. Then I open the file and CF view using the unsteady results (reconstruction required) option. After completing this process, it is showing the error “input error in Unsteady_lamda_Lpp_C1.cfv: Cannot read file or file doesn’t exist”.  Please let me how to resolve this issue.

With regards,

Paresh Halder