[eternityboy]

Could anyone say any theory about translationDamper (linearDamper)?

i see int DTCHull theory
one is 8596
and AngularDamper is 11586?

so, where is point of these values?

and any suggestion to choose innerDistance and outerDistance?
like a percentage of the hull or something?

[Tobi]

Hi,

as far as I understood it ... InnerDistance is the area which is not deformed, outerDistance will be deformed

The values that are given for the dumper, I do not know exactly. In the source you find that it is in Nm so torque somehow. You can also find information in openfoamwiki.

Sent from my HTC One mini using CFD Online Forum mobile app

[eternityboy]

yeah... what is innderDistance and outer one - is quite clear.. the question was - how you choose it... like, for example I have body of 3 meters... should i take 0.3 for inner distance and 1 or 3 or somethings else for outer distance.. like, any recommendations on that..


on the wiki - the values of damping coefficient are in - N*s/m
guess i should check source code here

I believe there should be part of physics in these coefficients, ahhhah

[Tobi]

Dear Nikita,

okay now I got it. Unfortunately I cannot suggest you anything about the inner and outerDistance. In addition you are right. The units are in [Ns/m] as given in the header-files of the code. It is written:

// Damping coefficient (Ns/m)
scalar coeff_;

The restraintForce is then calculated by:

    restraintForce = -coeff_*motion.v();
    restraintMoment = Zero;

[eternityboy]

Yeah, and now its just "some kind of force", restrainForce, which equals to ...

have no idea of the roots

[Tobi]

Well, it is like a force acting against the motion. However, I am not sure about the roots. Once I made tests with 6DoF I realized that this value should be lower 1. Because! if it is larger than 1 you can have a force which is highter than the acting force and I got a backward rotating which was really destroying my numerical simulation. However, it might be that I made some mistakes in the setup but as you know, there is not much to set up in the restraining / constraining section.

Maybe you find something here: https://openfoamwiki.net/index.php/P...esh#Restraints

I am not too familiar with that topic so I am sorry not to give you more advice.