sloshing

Rezaslosh · July 15, 2009, 08:24

Hello all,

How can I give a sinosoidal motion(not angular) to a partially filled fuel tank?

michael_owen · July 15, 2009, 08:50

Apply your sinusoidal transverse acceleration in the buoyancy gravity vector using CEL.

ckleanth · July 15, 2009, 08:57

you could as well apply the sinusoidal mesh movement to the whole domain (obviously you need to write the movement with cartesian x, y coordinates with sin and cos expressions)

Rui · July 15, 2009, 09:59

That is, theoretically, obviously the same (you can't differentiate whether you are being accelerated or under a force field *)
But I wonder if both cases are numerically handled by CFX in the same way

* I've heard of a theory that says that the Earth gravity force doesn't exist, but in fact the Earth radius is expanding with an acceleration of 9.8m/s2.

michael_owen · July 15, 2009, 10:24

If you use ckleanth's method, which I have used many times, be sure to create a subdomain for the entire domain and specify the rigid body mesh motion on it, so that you avoid distortion of the internal mesh due to "mesh inertia", and the associated numerical errors associated with it. In other words, if you only specify the motion on the external surfaces, that motion will only diffuse into the internal mesh, distorting it, rather than carrying it along whole "for the ride", so to speak.

Rezaslosh · July 29, 2009, 03:24

I was on holydays. I will check the results and compare them with some available theoritical and experimental data and get back here soon.

July 15, 2009, 08:24	sloshing	#1
Rezaslosh New Member Join Date: Jul 2009 Posts: 7 Rep Power: 16	Hello all, How can I give a sinosoidal motion(not angular) to a partially filled fuel tank?

July 15, 2009, 08:57		#3
ckleanth Senior Member George Join Date: Mar 2009 Location: Birmingham, UK Posts: 257 Rep Power: 18	you could as well apply the sinusoidal mesh movement to the whole domain (obviously you need to write the movement with cartesian x, y coordinates with sin and cos expressions) __________________ Top 4 tips 1. Knowledge is everything and Ignorance is dangerous. 2. Understand your limitations and try to eliminate them. 3. Get yerself a bike and hoon the chuffer. You will soon learn why dogs like to hang their heads out the car window. 4. Please before asking any questions on how to run simulations in CFX, go though all the tutorials

July 15, 2009, 09:59		#4
Rui Member Rui Igreja Join Date: Mar 2009 Location: Aveiro Posts: 68 Blog Entries: 1 Rep Power: 17	That is, theoretically, obviously the same (you can't differentiate whether you are being accelerated or under a force field ) But I wonder if both cases are numerically* handled by CFX in the same way * I've heard of a theory that says that the Earth gravity force doesn't exist, but in fact the Earth radius is expanding with an acceleration of 9.8m/s2. __________________ Rui

July 29, 2009, 03:24	Thank you all	#6
Rezaslosh New Member Join Date: Jul 2009 Posts: 7 Rep Power: 16	I was on holydays. I will check the results and compare them with some available theoritical and experimental data and get back here soon.

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July 15, 2009, 08:50		#2
michael_owen Senior Member Michael P. Owen Join Date: Mar 2009 Posts: 196 Rep Power: 17	Apply your sinusoidal transverse acceleration in the buoyancy gravity vector using CEL.

July 15, 2009, 10:24		#5
michael_owen Senior Member Michael P. Owen Join Date: Mar 2009 Posts: 196 Rep Power: 17	If you use ckleanth's method, which I have used many times, be sure to create a subdomain for the entire domain and specify the rigid body mesh motion on it, so that you avoid distortion of the internal mesh due to "mesh inertia", and the associated numerical errors associated with it. In other words, if you only specify the motion on the external surfaces, that motion will only diffuse into the internal mesh, distorting it, rather than carrying it along whole "for the ride", so to speak.