I will explain my problem here in detail.
my specific problem is related to a solid 3D pipe with a fluid flowing through it (heat transfer and laminar flow modules used here.)
- I want to change the inlet temperature(Ti) at each time step(t).
- The new inlet temperature is a function of the outlet temperature(To) from the previous time step.
- I have experimented with the "prev" operator and "boundary probe". This works fine for simple functions but for more complex functions I believe Matlab is required. I may be wrong here and would appreciate any advice.
- With Matlab I could generate a for loop so that for each iteration the inlet temperature was updated.
- The problem i have with this is that the initial conditions i.e. the temperature of the domain is not updated with each loop and the temperature distribution in the pipe for my particular problem is non-negligible.
- Is there a computationally more efficient way of solving this problem other than creating a new solver for each time step using the initial conditions of the last iteration.
I have searched the comsol forums but have not managed to find a solution there. I am sure others have had similar problems in the past and I would greatly appreciate their help.
Hi Markus, thanks for the reply.
In order for me to explain myself i need to be a bit precise here. I want to use the temperature output from the boundary probe (To) as the input value for a hot water tank, which i can represent by a linear equation (see below). But the problem is the storage tank temperature(Ts) is a function of its previous temperature(Ts(t-1)), so those values need to be stored somewhere (this is where i get lost).
The problem (in general) which i somehow need to fit into the one line in comsol is as follows.
First the boundary probe temperature needs to be converted into energy:
Qo=(To-Ti)*m*cf
Then this is used in solving the new tank temperature (don't mind the other variables):
Ts(t)=Ts(t-1)+(timestamp./(Mt*Cf)).*(Qo(t)-load(t)-(Utnk*Atnk*(Ts(t-1)-Tain(t)))
Now i can use this temperature as the next inlet temperature Ti=Ts
This is only the beginning of the system I want to simulate, I would also like to include heat exchangers, controllers etc. all of which means more lines of code, and this is why i assume maybe I should use a combination of "prev" operator and "boundary probe" as well as Matlab.
The thermal boundary conditions for the pipe (comsol model) and tank are based on experimentally recorded data (ambient temperatures, solar radiation etc.) at discrete time steps.
I have succeeded using a number of boundary probe and global variable probes and have managed to avoid requiring Matlab.
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