Water and air simulation

kubajed · October 26, 2017, 13:53

Hi
I don't have ANSYS CFX module, so I want ask you for help. I need to show that water have bigger heat capacity than air. It could be a simple simulation of box filled with water and air and all heated for 15sec. After that time a photo with temperature distribution. The same in opposite situation (cooling). Could I rely on your help?

ghorrocks · October 26, 2017, 19:07

You could ask for our help but I cannot see what help we can give you.

The heat capacity is just density*Cp, so if you want to show water has a bigger heat capacity than air you can just look up the material properties and work it out.

kubajed · October 27, 2017, 13:45

You're right, I could compare heat capacities. But I need to do an "experiment" which shows that water keeps heat longer than air. Simulation will be great in that manner.

ghorrocks · October 28, 2017, 07:07

How about you have a box completely filled with air. The walls are a heat source and add 100W of heat for 10s. Then have a look at the temperature this generates. Repeat the simulation with water in the box and you will find the air is much hotter for the same amount of heat compared to the water.

This is a very simple simulation which shows the effect of the different heat capacities.

kubajed · October 28, 2017, 07:47

As I said I haven’t got ANSYS CFX and that is the biggest problem.

ghorrocks · October 28, 2017, 08:31

Then why are you posting on a CFX forum?

You can get a student version of CFX from ANSYS. I think it is free for students.

But you don't need CFX to do what you are talking about. Just write a simple thing which gives the temperature versus time of the air/water volume in my previous post. You can do this in a simple excel spreadsheet - you don't need CFD for this.

kubajed · October 28, 2017, 10:13

I am posting here because people here have got that program, me not. Yes, I could do simple CALCULATION in excel, but I need visible method like SIMULATION (plots aren't simulation).

ghorrocks · October 28, 2017, 18:00

Plots are simulation, just like CFD is simulation. CFD is just a more complex form of simulation.

So what are you asking for? Do you want somebody to do the simulation for you and you send the results?

Please see my previous post - "You can get a student version of CFX from ANSYS. I think it is free for students." This sounds like the best way forward to me.

October 26, 2017, 13:53	Water and air simulation	#1
kubajed New Member Join Date: Oct 2017 Posts: 4 Rep Power: 9	Hi I don't have ANSYS CFX module, so I want ask you for help. I need to show that water have bigger heat capacity than air. It could be a simple simulation of box filled with water and air and all heated for 15sec. After that time a photo with temperature distribution. The same in opposite situation (cooling). Could I rely on your help?

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October 26, 2017, 19:07		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	You could ask for our help but I cannot see what help we can give you. The heat capacity is just density*Cp, so if you want to show water has a bigger heat capacity than air you can just look up the material properties and work it out.

October 27, 2017, 13:45		#3
kubajed New Member Join Date: Oct 2017 Posts: 4 Rep Power: 9	You're right, I could compare heat capacities. But I need to do an "experiment" which shows that water keeps heat longer than air. Simulation will be great in that manner.

October 28, 2017, 07:07		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	How about you have a box completely filled with air. The walls are a heat source and add 100W of heat for 10s. Then have a look at the temperature this generates. Repeat the simulation with water in the box and you will find the air is much hotter for the same amount of heat compared to the water. This is a very simple simulation which shows the effect of the different heat capacities.

October 28, 2017, 07:47		#5
kubajed New Member Join Date: Oct 2017 Posts: 4 Rep Power: 9	As I said I haven’t got ANSYS CFX and that is the biggest problem.

October 28, 2017, 08:31		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Then why are you posting on a CFX forum? You can get a student version of CFX from ANSYS. I think it is free for students. But you don't need CFX to do what you are talking about. Just write a simple thing which gives the temperature versus time of the air/water volume in my previous post. You can do this in a simple excel spreadsheet - you don't need CFD for this.

October 28, 2017, 10:13		#7
kubajed New Member Join Date: Oct 2017 Posts: 4 Rep Power: 9	I am posting here because people here have got that program, me not. Yes, I could do simple CALCULATION in excel, but I need visible method like SIMULATION (plots aren't simulation).

October 28, 2017, 18:00		#8
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Plots are simulation, just like CFD is simulation. CFD is just a more complex form of simulation. So what are you asking for? Do you want somebody to do the simulation for you and you send the results? Please see my previous post - "You can get a student version of CFX from ANSYS. I think it is free for students." This sounds like the best way forward to me.