How can I make a CFD simulation to calculate energy absorbed by water?

Laithalnaser · September 11, 2018, 06:38

How can I make a CFD simulation to calculate energy (K.E) absorbed by water from a moving object inside it producing work (P.E).
Similarly to the paddle wheel experiment by James Joules.

P.S. Its for a school project! please help

Thank you for your time!

LuckyTran · September 12, 2018, 08:42

You need to be way more specific. What software you are using, etc. What is your actual geometry? How do you plan to model it?

Let's suppose I was simulating the paddle wheel experiment by Joules. I'd mesh me a circular tank with some walls to represent the paddle wheel. Then I'd go into one of my favorite CFD programs. I'd assign a rotational velocity to some of these walls. I could assign it to the paddle wheel or I can just assign it to the tank walls and have the paddle wheel stationary and the tank spinning (not what Joule did, but you get the same effect).

I'd probably pick constant density water with all material properties constant just to simplify things. Then I'd set up a bunch of settings and calculate it steady state as a laminar flow and just integrate over the volume the viscous dissipation and I'll get a number with units of Watts. In some software like Star-CCM the viscous dissipation is always calculated. In Fluent it must be activated. In OpenFOAM you have to do some more things. And then you could spice it up even more and do a transient simulation to actually do what Joule did. Set the initial temperature to ambient condition and do many many many time-steps and watch the temperature rise to the boiling point. Of course if I use a constant density equation of state, I'll never get to see the water boil the same way as Joule.

September 11, 2018, 06:38	How can I make a CFD simulation to calculate energy absorbed by water?	#1
Laithalnaser New Member Laith Join Date: Sep 2018 Posts: 1 Rep Power: 0	How can I make a CFD simulation to calculate energy (K.E) absorbed by water from a moving object inside it producing work (P.E). Similarly to the paddle wheel experiment by James Joules. P.S. Its for a school project! please help Thank you for your time!

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September 12, 2018, 08:42		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,761 Rep Power: 66	You need to be way more specific. What software you are using, etc. What is your actual geometry? How do you plan to model it? Let's suppose I was simulating the paddle wheel experiment by Joules. I'd mesh me a circular tank with some walls to represent the paddle wheel. Then I'd go into one of my favorite CFD programs. I'd assign a rotational velocity to some of these walls. I could assign it to the paddle wheel or I can just assign it to the tank walls and have the paddle wheel stationary and the tank spinning (not what Joule did, but you get the same effect). I'd probably pick constant density water with all material properties constant just to simplify things. Then I'd set up a bunch of settings and calculate it steady state as a laminar flow and just integrate over the volume the viscous dissipation and I'll get a number with units of Watts. In some software like Star-CCM the viscous dissipation is always calculated. In Fluent it must be activated. In OpenFOAM you have to do some more things. And then you could spice it up even more and do a transient simulation to actually do what Joule did. Set the initial temperature to ambient condition and do many many many time-steps and watch the temperature rise to the boiling point. Of course if I use a constant density equation of state, I'll never get to see the water boil the same way as Joule.