is it possible to include surface tension in DEM?

synuk75 · July 13, 2018, 06:53

Hi guys,

apart from the drag and lift forces exerted by the fluid over the particles I woul like to simulate capillary effects. is it possible using DEM?. I only found the option using eulerian-eulerian models...
Thank you

ping · July 21, 2018, 02:14

dem particles are relatively large solids so the concept of surface tension in fluids as caused by molecular attraction does not apply so please explain what force you are wanting to simulate

synuk75 · July 23, 2018, 18:17

Hi,

I really appreciate your help,

I am trying to simulate wet sand. sand particles remain together because of capillary forces, (that is why we can build sand castles in the beach). i have decided to simulate this capillary forces including linear cohesion since STAR doesnt allow me to include surface tensions.

what i am realy straggling is that although the water in between the grain particles only occupies a fraction of the continuum (because of the solid grains), when i represent the volume fraction of water the value is 1 all over the domain. however the void fraction seems to be ok and give me values between 0.25 and 1 over the continuum domain. any ideas about what i am doing wrong?

i posted it in another thread but no reponse so far.

thank you very much,

ping · July 24, 2018, 00:07

you can certainly turn on surface tension when dem is enabled but normally surface tension needs two fluids to be present eg in your case air and water and so this is what causes the attractive forces and if there is no air then i would expect there is no surface tension force but this is something i have never explored

July 13, 2018, 06:53	is it possible to include surface tension in DEM?	#1
synuk75 New Member Miguel Join Date: Apr 2018 Posts: 8 Rep Power: 8	Hi guys, apart from the drag and lift forces exerted by the fluid over the particles I woul like to simulate capillary effects. is it possible using DEM?. I only found the option using eulerian-eulerian models... Thank you

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July 21, 2018, 02:14		#2
ping Senior Member Ping Join Date: Mar 2009 Posts: 556 Rep Power: 20	dem particles are relatively large solids so the concept of surface tension in fluids as caused by molecular attraction does not apply so please explain what force you are wanting to simulate

July 23, 2018, 18:17		#3
synuk75 New Member Miguel Join Date: Apr 2018 Posts: 8 Rep Power: 8	Hi, I really appreciate your help, I am trying to simulate wet sand. sand particles remain together because of capillary forces, (that is why we can build sand castles in the beach). i have decided to simulate this capillary forces including linear cohesion since STAR doesnt allow me to include surface tensions. what i am realy straggling is that although the water in between the grain particles only occupies a fraction of the continuum (because of the solid grains), when i represent the volume fraction of water the value is 1 all over the domain. however the void fraction seems to be ok and give me values between 0.25 and 1 over the continuum domain. any ideas about what i am doing wrong? i posted it in another thread but no reponse so far. thank you very much,

July 24, 2018, 00:07		#4
ping Senior Member Ping Join Date: Mar 2009 Posts: 556 Rep Power: 20	you can certainly turn on surface tension when dem is enabled but normally surface tension needs two fluids to be present eg in your case air and water and so this is what causes the attractive forces and if there is no air then i would expect there is no surface tension force but this is something i have never explored