Water in the tank increase

mailoan2306 · November 14, 2020, 04:04

Hi every one,

I am simulating the ship in irregular wave.
I am model the tank include sponge layer with type wave absorbing at the end of the tank.
However, after a long time simulation about 600 seconds (the water growing up every 60 seconds). The water in the tank increase compares with the initial.
So how can fix the volume of water the same as the initial state
The picture has been located in the below links
Thank you so much for your help

Setup picture: https://imgur.com/a/vskWBZ9
The volume of water at the initial state: https://imgur.com/a/4ThDkQO
The volume of water after 600s: https://imgur.com/a/VAmExxj

M.Nazrin · November 14, 2020, 11:43

Hi Thi Loan,

What is the boundary condition type at the sponge layer? i believe there is no outflow in the domain thus the water level keep increasing.

mailoan2306 · November 14, 2020, 11:51

Thank you four your answer,

The boundary condition of the outlet is outflow as shown in the below link

https://imgur.com/a/slD5L7C

M.Nazrin · November 15, 2020, 21:44

can you check the mesh flow rate at outflow boundary using analyze tab > probe > mesh dependent history > 'outflow boundary'.

mailoan2306 · November 15, 2020, 23:31

Thank you for your reply.
I checked the volume flow rate follow you are recommendation shown in the picture in the below link.
I realize that the volume changed frequently. But I didn't understand. It is different when I use the coupled motion and non-moving the object. For example, when I use non-moving the volume of water not change but when I use coupled motion the volume changes it can lose and grow up in the tank.

Volume flow rate: https://imgur.com/a/GykOmVO

M.Nazrin · November 16, 2020, 02:55

"For example, when I use non-moving the volume of water not change but when I use coupled motion the volume changes it can lose and grow up in the tank."

I am not sure what happen for your case. Supposed, fluid volume should be consistent whether you use non-moving/moving object. Perhaps you should forward this to official support? Sorry for not helping.

What happen if you use moving object without wave absorbing component?

mailoan2306 · November 16, 2020, 03:11

No no, I am sorry. I mistook

I checked it again. All cases were changed the volume of water it can be lost or grow up.
I will check in case no-wave absorbing.
Thank you for your advice.

November 14, 2020, 04:04	Water in the tank increase	#1
mailoan2306 New Member MAI THI LOAN Join Date: Mar 2020 Location: Korea Posts: 17 Rep Power: 6	Hi every one, I am simulating the ship in irregular wave. I am model the tank include sponge layer with type wave absorbing at the end of the tank. However, after a long time simulation about 600 seconds (the water growing up every 60 seconds). The water in the tank increase compares with the initial. So how can fix the volume of water the same as the initial state The picture has been located in the below links Thank you so much for your help Setup picture: https://imgur.com/a/vskWBZ9 The volume of water at the initial state: https://imgur.com/a/4ThDkQO The volume of water after 600s: https://imgur.com/a/VAmExxj

November 16, 2020, 03:11		#7
mailoan2306 New Member MAI THI LOAN Join Date: Mar 2020 Location: Korea Posts: 17 Rep Power: 6	No no, I am sorry. I mistook I checked it again. All cases were changed the volume of water it can be lost or grow up. I will check in case no-wave absorbing. Thank you for your advice. M.Nazrin likes this.

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November 14, 2020, 11:43		#2
M.Nazrin Member nazrin Join Date: Apr 2016 Posts: 35 Rep Power: 10	Hi Thi Loan, What is the boundary condition type at the sponge layer? i believe there is no outflow in the domain thus the water level keep increasing.

November 14, 2020, 11:51		#3
mailoan2306 New Member MAI THI LOAN Join Date: Mar 2020 Location: Korea Posts: 17 Rep Power: 6	Thank you four your answer, The boundary condition of the outlet is outflow as shown in the below link https://imgur.com/a/slD5L7C

November 15, 2020, 21:44		#4
M.Nazrin Member nazrin Join Date: Apr 2016 Posts: 35 Rep Power: 10	can you check the mesh flow rate at outflow boundary using analyze tab > probe > mesh dependent history > 'outflow boundary'.

November 15, 2020, 23:31		#5
mailoan2306 New Member MAI THI LOAN Join Date: Mar 2020 Location: Korea Posts: 17 Rep Power: 6	Thank you for your reply. I checked the volume flow rate follow you are recommendation shown in the picture in the below link. I realize that the volume changed frequently. But I didn't understand. It is different when I use the coupled motion and non-moving the object. For example, when I use non-moving the volume of water not change but when I use coupled motion the volume changes it can lose and grow up in the tank. Volume flow rate: https://imgur.com/a/GykOmVO

November 16, 2020, 02:55		#6
M.Nazrin Member nazrin Join Date: Apr 2016 Posts: 35 Rep Power: 10	"For example, when I use non-moving the volume of water not change but when I use coupled motion the volume changes it can lose and grow up in the tank." I am not sure what happen for your case. Supposed, fluid volume should be consistent whether you use non-moving/moving object. Perhaps you should forward this to official support? Sorry for not helping. What happen if you use moving object without wave absorbing component?