Hi,
I've been reading about fluid subdomains and I have understood how to create them and how to edit their parameters but I have still one question left.
In my case (a heat exchanger) I define both subdomains. One would be water and the other one will be a mixture of gases which I define by setting 34% of air, 33% of methane, 20% of methane and 13% of Nitrogen. Then in the LIDs inlets I would have to set again that from one is entering water and from the second one I repeat and enter again that mixture...
So, what difference would it be if I simply entered the parameters for the inlets without creating the fluid subdomains?
(It is useful for me because it helps me to see if both subdomains are isolated, but that's all, after that I erase them).
Thanks in advance
Yes, with air on one side vs a mixture of gases on the other side there is no need for subdomains because they are all gases.
If you define the initial condition has having a concentration of 100% air, and then inject a mixture of gases you can trace how uniformly or how fast the air is displaced by the mixture.
I often use fluid volumes as initial conditions for mixtures (or initial temperatures to reduce time to convergence). So you could define one volume as air, and another as the mixture without using subdomains.
I've never tried using a subdomain to set initial conditions of a volume so I can't be 100% sure about your 2nd question. But I would guess that it would simply make that volume air, and then exchange it with the gaseous mixture. There may be other benefits of using a subdomain in this situation that others could highlight.