## Towed cable calculations

## Towed cable calculations

(OP)

Hi all,

I'm trying to work out an equation of motion for a project I'm working on. It's a towed system with a cable and mass at the end and I would like to be able to come up with an equation of motion for the system. I have the mass' drag values from some COMSOL simulations, but i'm feeling like my knowledge of steady state controls systems is lacking (I'm a structures guy) and I'm feeling kind of stupid.

Can someone direct me to a good example of how to go about developing this? A link? A textbook? something that explains how to set up the equation? Been out of school a long time so this feels really alien to me.

thanks!

I'm trying to work out an equation of motion for a project I'm working on. It's a towed system with a cable and mass at the end and I would like to be able to come up with an equation of motion for the system. I have the mass' drag values from some COMSOL simulations, but i'm feeling like my knowledge of steady state controls systems is lacking (I'm a structures guy) and I'm feeling kind of stupid.

Can someone direct me to a good example of how to go about developing this? A link? A textbook? something that explains how to set up the equation? Been out of school a long time so this feels really alien to me.

thanks!

## RE: Towed cable calculations

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

## RE: Towed cable calculations

I've got a towed system on the end of a cable pulled at 3 knots. I've got to find an equation of motion for the force needed to pull the system with the drag from the cable, the system and i've been told we need to be able to predict the motion using kinematic equations for the dynamics of the system as well.

I'm looking at papers published in ocean engineering to understand the concepts, and I see the math, but not sure how to relate this to my situation - mostly because I don't have an ocean engineering background.. it's like a baker looking at a fish - he knows the concept of how to cook, but this is totally different thing. I'm looking for a reference where I can learn how to set up this system logically and correctly without going back to school to get another degree, I guess is what i"m looking for.

Any help would be great, thanks!

## RE: Towed cable calculations

Basically i could model it all sorts of level of detail, whereas equations might be more difficult.

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

## RE: Towed cable calculations

catenary no

paravane a certain type

wave effects no

submerged

compliance not sure how to determine that.

I understand modeling it is possible, but i"m looking for how to learn how to do this. I imagine this was Ocean engineering 101, right?

Thanks for your help!

## RE: Towed cable calculations

I suspect that a draggy cable is a computational nightmare so i'll ignore that.

OK, that's enough random thoughts.

Draw the thing up in plan viwe and front view, work out your free body diagrams, using d'Alemebert forces, and you may have something usable.

Since I can't tell what level of fidelity you are after i can't say whetehr that is enough, but it is certainly an essential first step.

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

## RE: Towed cable calculations