Hello,
I am pretty new with this CFD topic.
I already read plenty articles and checked tutorials regarding this topic.
I am about to design an underwater towed body (close to the surface, a part is surface piercing) and I want to get informations regarding the resistance of the hull. For this I was looking for comparable models. The best I found was a Torpedo with an wetted surface very close to my body. I set up a simulation and now I have results, but I am not really sure, if everything I set up was right. So I set up a simulation for the Torpedo as well (same settings), but the average Drag is twice as much as reported in the paper. To specify my questions:
1. There are plenty peaks within the Drag curve shouldn´t (if all goes right) the curves become "flat"?
2. I am not sure about the boundary settings, orientated at the boat tutorial.
I added some pictures. If you need more information, just let me know.
Thanks for your help
Hi Jan,
To start with, no, your simulation doesn't seem to have converged - those peaks look rather suspicious. If there is a steady solution for your simulation, the drag should indeed converge to a constant value. Those peaks look like some numerical artefact, but still, taking a closer look at your results (velocity field, pressure, volume fraction, etc.) as a function of time might be helpful.
What settings to choose depends on your problem: Froude number, Reynolds number, whether to expect cavitation, streaking, etc. Sorry, I couldn't make much of the screenshots you included. Are you using a steady or an unsteady solver? RANS, LES, DNS, laminar? Domain size relative to towed body size? Symmetry? Rigid body motion/moving mesh?
You mentioned a paper that reported drag values for this torpedo. I think the best way to go would be to try and reproduce these results first, perhaps contact the authors to find out which settings they used.
Hope this helps,
Sita
Hello, thanks for your answer.
The Simulation is still running but no "result".
Some more information:
RANS
Domain is [-6; -7; -10], [18; 7; 3] (in m)
Torpedo is 3m long with D=0,29m
NO Symmetry
current and wind set to 1m/s running through the domain
VoF Wave damping zone of 15m
Greets Jan
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