CFD modelling of flow in flexible pipes

muntypro · February 7, 2012, 10:45

Hello all, I'm new to this forum and joined since I have a CFD challenge.
I need to model the dynamic flow in flexible pipes and a quick google did not throw up any related papers, but I'm sure there are some.
The typical environment is a flat hose, like a fire hose, that is inflated by water pressure. I can't claim to know much about CFD applications since s/w has changed drastically since I did my degree in Mech Eng.
Can anyone indicate what package would be best used for this please and why? I'm familiar with Matlab/Simulink but this is a whole league different to my expertise. Is there anyone in the forum who wants to do some freelance work, since I can guarantee it will be more time and cost efficient that me buying/learning how to use a recommended package?

Q's, advice & comments much appreciated. Thanks.

rmh26 · February 9, 2012, 13:38

Charles Peskin and Oliver Jensen have done a lot of work in this field. I'm not sure if any commercial software can handle this all that accuratley. You might be able to get some of Peskin's codes online. What is the nature of this research?

muntypro · March 9, 2012, 11:41

Thanks for the advice and sorry for not replying for a month! I got in touch with Charles and got some further advice. The nature of the research is to model the fluid dynamics and elastometric wall properties of a long fire-like hose when used for lifting heavy equipment (similar to airbags used in place of jacks or hyrdaulic equipment at accidents).

rmh26 · March 12, 2012, 21:17

Do you need to do dynamic modeling (looking at the initial inflation) or just static cases?

muntypro · March 13, 2012, 04:16

Yes, I do need to do dynamic modelling. Initially the hose will be flat and a constant evenly distributed pressure applied along its length. When water is admitted from one end it will inflate the hose to a non-circular profile, and progress along the length.
I think full inflation will only occur when the whole length has some water in it (let's call this 'lift-off' time). A certain time later, depending of the delivery pump pressure and flow rate the hose will have an approximately circular shape, depending on the constant external side pressure applied.
The dynamic part I'm most interested in is the initial phase where fluid runs along the length before lift off. Let's assume the hose is inelastic if it's made of an impregnated woven glass fibre cloth.
Also let's assume the external body applying pressure is non-rigid (eg sacks of sand or ballast) so lifting at one end is not influenced by the other.
Is there an applied external pressure where the fluid will not flow along the length and instead lift the weight and form an approximately circular profile that will then work its way along the length?

(I guess another example of this is the inflation of balloons. Standard profile ones inflate evenly in all directions whilst long ones inflate along their length -handy for making into party shapes!. This is highly influenced by the elastic properties in circumferential and longitudinal directions, and the aspect ratio.)

February 7, 2012, 10:45	CFD modelling of flow in flexible pipes	#1
muntypro New Member Matthew Join Date: Jan 2012 Posts: 3 Rep Power: 14	Hello all, I'm new to this forum and joined since I have a CFD challenge. I need to model the dynamic flow in flexible pipes and a quick google did not throw up any related papers, but I'm sure there are some. The typical environment is a flat hose, like a fire hose, that is inflated by water pressure. I can't claim to know much about CFD applications since s/w has changed drastically since I did my degree in Mech Eng. Can anyone indicate what package would be best used for this please and why? I'm familiar with Matlab/Simulink but this is a whole league different to my expertise. Is there anyone in the forum who wants to do some freelance work, since I can guarantee it will be more time and cost efficient that me buying/learning how to use a recommended package? Q's, advice & comments much appreciated. Thanks.

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February 9, 2012, 13:38		#2
rmh26 Member Join Date: Jul 2011 Posts: 59 Rep Power: 14	Charles Peskin and Oliver Jensen have done a lot of work in this field. I'm not sure if any commercial software can handle this all that accuratley. You might be able to get some of Peskin's codes online. What is the nature of this research?

March 9, 2012, 11:41		#3
muntypro New Member Matthew Join Date: Jan 2012 Posts: 3 Rep Power: 14	Thanks for the advice and sorry for not replying for a month! I got in touch with Charles and got some further advice. The nature of the research is to model the fluid dynamics and elastometric wall properties of a long fire-like hose when used for lifting heavy equipment (similar to airbags used in place of jacks or hyrdaulic equipment at accidents).

March 12, 2012, 21:17		#4
rmh26 Member Join Date: Jul 2011 Posts: 59 Rep Power: 14	Do you need to do dynamic modeling (looking at the initial inflation) or just static cases?

March 13, 2012, 04:16		#5
muntypro New Member Matthew Join Date: Jan 2012 Posts: 3 Rep Power: 14	Yes, I do need to do dynamic modelling. Initially the hose will be flat and a constant evenly distributed pressure applied along its length. When water is admitted from one end it will inflate the hose to a non-circular profile, and progress along the length. I think full inflation will only occur when the whole length has some water in it (let's call this 'lift-off' time). A certain time later, depending of the delivery pump pressure and flow rate the hose will have an approximately circular shape, depending on the constant external side pressure applied. The dynamic part I'm most interested in is the initial phase where fluid runs along the length before lift off. Let's assume the hose is inelastic if it's made of an impregnated woven glass fibre cloth. Also let's assume the external body applying pressure is non-rigid (eg sacks of sand or ballast) so lifting at one end is not influenced by the other. Is there an applied external pressure where the fluid will not flow along the length and instead lift the weight and form an approximately circular profile that will then work its way along the length? (I guess another example of this is the inflation of balloons. Standard profile ones inflate evenly in all directions whilst long ones inflate along their length -handy for making into party shapes!. This is highly influenced by the elastic properties in circumferential and longitudinal directions, and the aspect ratio.)