# A water tank subjected to frame motion

 Register Blogs Members List Search Today's Posts Mark Forums Read

 August 7, 2022, 04:39 A water tank subjected to frame motion #1 New Member   Abdullah Join Date: Aug 2022 Posts: 2 Rep Power: 0 Hi, I am simulating a water tank subjected to discontinous velocity. At the point of discontinuity a pressure surge is seen in "area weighted average Max pressure" curve then it stablizes. I just want to know that is this term corrwcr or not. Example: Velocity changes at 10secs (linear Velocity profile is used) At 9.995 pressure is 5000Pa At 10.005 pressure is 5500 Pa At 10 pressure is 120 KPa

 August 7, 2022, 06:03 #2 New Member   Join Date: Aug 2022 Posts: 1 Rep Power: 0 Which CFD software do you use?

 August 7, 2022, 06:21 #3 New Member   Abdullah Join Date: Aug 2022 Posts: 2 Rep Power: 0 I am using ansys fluent

 August 8, 2022, 11:23 #4 Senior Member   Join Date: Jul 2009 Posts: 333 Rep Power: 17 Are you familiar with the impulse-momentum form of Newton's 2nd law? You have a momentum change when the velocity changes - if the change is very rapid then you can easily generate an impulsive type force. A better way to think of it is that you would need to apply a large impulse to generate the observed or desired change in velocity. But fundamentally you have the impulse I = (Mass)x(Velocity2 - Velocity1). The impulse is the integral of the applied force over the time applied, so for your case it could be approximated as 0.5*(Timestep)*(120000 Pa - 5000 Pa)*(Area of application). I don't know your setup, so that's as far as I can go. But you should be able to work out the rest.

 Tags frame motion, pressure and velocity, sloshing tank, surge tank