Marine - Recent Threads

Fine Marine: The machine's VDH is not found.

Gaurav — Mon, 05 May 2025 07:39:21 GMT

To use the Fine Marine solver, a separate license file, including the machine's VDH, is required. Errors may occur when checking the license, indicating an incorrect or missing machine VDH. Resolving this issue is necessary to ensure the Fine Marine solver functions correctly.

https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1OPP000001718T2AQ&pageName=ArticleContent

Article ejection

saji vf — Mon, 24 Feb 2025 06:27:11 GMT

Hello sir,

Hope you are doing well,

can we do Article ejection for underwater vehicles?

1.We wanted to move article with propeller rotation along underwater vehicle moving.

2. is there any similar case study has been done in fine marine?

Thank you.

RE: Article ejection

Benoit Mallol — Mon, 03 Mar 2025 09:15:47 GMT

Here is a test case attached.

It consists of 2 simulations, the second one being the restart of the first one.

If you run the simulation, you will notice that the forces are quite oscillatory in the second simulation. This is expected since the object is in a confined environment and a lot of physics happens in this region where overlapping meshes are present.

Best regards

RE: Article ejection

Benoit Mallol — Mon, 03 Mar 2025 09:12:11 GMT

community.cadence.com/.../2D_5F00_Submarine_5F00_Torpedo_5F00_Overset.tar.gz

RE: Article ejection

saji vf — Thu, 27 Feb 2025 03:45:42 GMT

Hello Thank you ,

is there any example case that did in finemarine similar to this case that can be shared ?

we did the overset mesh for the geometry but confused setting up the solver.

RE: Article ejection

Benoit Mallol — Tue, 25 Feb 2025 14:27:20 GMT

Hello,

do you mean ejecting an object from the underwater vehicle that is moving forward, right?
If so, Fine Marine has already seen such projects. And you can indeed do it using overset method, in 2 steps:

First simulation: the underwater vehicle is moving forward and the object is inside the underwater vehicle following the motion of this vehicle (important to already define 2 bodies and place the 2nd body in an overlapping domain).

Second simulation: once the first is converged, we can eject the object by giving its own motion. the difficulty here will be the time step and the cell size in the confined region in between the object and the vehicle.

Best regards,

Benoit

RE: water entry

Benoit Mallol — Mon, 09 Sep 2024 07:09:06 GMT

You're welcome!

FYI, you are allowed to contact your local support. A dedicated team can also answer your questions, maybe even faster that what we can do here. :-)

water entry

saji vf — Fri, 30 Aug 2024 08:42:21 GMT

Hello,

can we do missile water entry case 3D in fine marine ,

1.if we can do how do we proceed through overset meshing (a case file if possible ) or case settings.

2. any validation done in fine marine?

Thank you.

RE: water entry

saji vf — Mon, 09 Sep 2024 03:56:56 GMT

Thank you for the info :-)

RE: water entry

Benoit Mallol — Fri, 06 Sep 2024 08:34:35 GMT

I see that all your DOF are fixed except Rz. How can it fall in the water? It will just rotate around (0,0,0). It can indeed hit the water thanks to the rotation but the object will continue to rotate forever.

RE: water entry

saji vf — Fri, 06 Sep 2024 08:01:26 GMT

Yes my cylinder should fall into the water at 40m/s for this my setup is correct right?

RE: water entry

Benoit Mallol — Fri, 06 Sep 2024 07:49:28 GMT

Hi,

You setup is basically correct. Here your cylinder will rotate around the Reference point (0,0,0) and it is above the water line. So you are not going to simulate water entry here. It will just rotate in the water. Maybe you want to put the Tz solved to let it fall?

Best regards,

Benoit

RE: water entry

saji vf — Thu, 05 Sep 2024 10:59:42 GMT

community.cadence.com/.../to_5F00_send.zip

Can you please check the case setup that i did for water entry at 0 deg & reset the setup in case it is wrong

Thank you.

RE: mooring lines

Benoit Mallol — Thu, 05 Sep 2024 08:20:30 GMT

Hi,

Mooring lines are quite limited for the moment in Fine Marine. But we did have a catenary approach but we had to end the partnership with our partner who developed this technique.

Hence, at the moment, we are working on developing this ourselves maybe re using open source libraries (like MoorDyn for instance).

Hence, I am not sure you can model this paper with Fine Marine at the moment.

Best regards,

Benoit

mooring lines

saji vf — Wed, 21 Aug 2024 05:02:39 GMT

Hello,

We are trying to simulate same as Paper "A procedure for the static analysis of cable structures following elastic catenary theory" by using mooring lines but in a different way by splitting the lines .

lines starts at body end and gets attached to a buoy with three spitted lines.
my doubt is how to visualize bending of those lines with due to loads in CFview.
can we simulate a catenary appraoch with mooring lines "Simulation Requirements for Tethered Sonar Array in Fine Marine".

Thank you.

[View:/cfs-file/__key/communityserver-discussions-components-files/123/A-procedure-for-the-static-analysis-of-cable-structures-following-elastic-catenary-theory-_2D00_-1_2D00_s2.0_2D00_S0020768314000031_2D00_main.pdf:640:480]

RE: water entry

Benoit Mallol — Thu, 05 Sep 2024 07:59:28 GMT

It can be any rotation in 3D. But remember that gravity will be involved and is given in Z direction.
So if you import or solve a rotation while entering the water, I guess it will be around Ry.

Positive or negative will depend on the orientation of your geometry in the setup. But if you do the exact same as on the picture you provided, I guess yes, it should be negative since it rotates from X to Z.

RE: water entry

saji vf — Thu, 05 Sep 2024 06:28:52 GMT

Then if my case is 3d the motion should be specified in Rz?

i.e., velocity in negative direction is this correct?

RE: water entry

Benoit Mallol — Wed, 04 Sep 2024 07:41:38 GMT

you're welcome :-)

Yes, your test can be done in 1 single computation and 3d setup is the same as 2d, no problem.

Best regards,

RE: water entry

saji vf — Wed, 04 Sep 2024 06:11:58 GMT

Thank you for the case setup :-)

can we do this in a single simulation, & for 3d case the setup is same ?

RE: water entry

Benoit Mallol — Tue, 03 Sep 2024 15:15:52 GMT

Hi,

Yes, you can perform such simulation. :-)

Overset is not mandatory because the entire domain could follow the missile (like in Tutorial 3 Advanced), but it is much better to use it to preserve the free surface clean in the far field since the missile is rotating as well.

We have already done it a couple of times, but I am not aware of any public validation case from our customers. In the past, we just created a dummy case to illustrate the project for a torpedo ejection from a submarine. You can find it attached. In this project, the missile is leaving water to the air, so it is the opposite of what you are willing to do but the numerical setup is exactly the same.

Best regards,

Benoitcommunity.cadence.com/.../2_5F00_domains_5F00_backup_5F00_24_2D00_06_2D00_2022_5F00_17h_2D00_40m_2D00_06s.zip

RE: PROPELLER CAVITATION

Benoit Mallol — Mon, 12 Aug 2024 16:27:55 GMT

Hi,

thanks for the information.

OMEGA is the Turbulent dissipation rate.

Another customer just reported that he is having difficulties with periodic conditions and cavitation when the cavitation pocket is crossing the periodic boundary... And it is not sure if we ever validated this scenario. Do you know if it is the case or not for your case?

Best regards,

Benoit

PROPELLER CAVITATION

saji vf — Mon, 29 Jul 2024 11:20:10 GMT

Hello,

we are trying to capture propeller cavitation for 10 deg with time step size=0.0028 for periodic mesh with K-omega (sst menter). we were able to observe the cavitation pattern after some 6000 time steps,

But in the residuals the K started to increase after 5000 time steps and OMEGA is fluctuating from the start(>1000). what could be the possible reason ?

The same periodic mesh was used in FLUENT Software too, got the required cavitation.

RE: PROPELLER CAVITATION

saji vf — Fri, 02 Aug 2024 09:54:45 GMT

In Fluent the sauer model is used similar to fine marine.

The periodic mesh in fine marine is validated for open water in our case. is Fine marine compatible for cavitation with periodic mesh ?

OMEGA in monitor relates to Turbulent frequency or Turbulent dissipation rate ?

The best practices of cavitation are set from tutorial and time step size taken is 0.028 for 10 degree and mesh quality is good enough with target y plus less than 1

RE: Turning circle

Benoit Mallol — Thu, 01 Aug 2024 15:57:49 GMT

Hi,

Yes, you must specificy the angular velocity too, otherwise the ship will not turn. However, in the restart you might want to deactivate the Tx DOF since the rotation and its speed will be handled by Rz? Unless you want to combine both effects.

Best regards,

Turning circle

saji vf — Thu, 25 Jul 2024 03:39:49 GMT

Hello ,

We are doing a turning circle simulation by giving radius and angular velocity in Rz motion (unsteady case) !

my doubt is:

1. how much time it will take to complete the simulation if my body is an appended model with mesh size of 11M?

2. i ran the simulation for around 200 sec with time step size of 0.023 .

3. can you guide me how to proceed further to get the convergence and complete the simulation.

Thank you .