hi all,

can anyone tell me how do i set up a batch reator with heating of the reactants(unsteady state problem). i dont quite understand how i can use fluent to solve this non-flow problem. siva

What is your source of thermal energy? Regardless, if you can quantify this, then you can define an energy source term (in W/m3) and apply this source term to your fluid zone (or subset of the fluid zone). Solve as a time-dependent problem.

thanks for the clarification, my source will be an electrical heater immersed in the reactor. could u please tell me how do i create a subset of the fluid zone(my problem is i need to heat the contents of a reactor which occupy 80% of the volume of the reactor to a certain temperature-i need to find the time taken for for various energy sources). thanks for you help. siva

As you previously indicated, this problem can be easily solved by assuming that the reactor is well mixed using heat balance (1st order ODE- see Seborg, Edgar, Mellichamp, "Process Dynamics and Control", Wiley, 1989...and many others). Hence, you do not really need CFD to solve this problem. However, if you would like to use CFD, as my implement my original suggestion implied, do the following: 1. if your reactor grid is complete, mark the region of the grid you would like to apply the source, using Adapt-->Region. This will give you approximately the subvolume you want and will only work neatly if your grid is hex. 2. if your reactor model is not built yet, create the sub-volume during the meshing process.

Once you have a separate fluid zone, you can apply the energy source term through the Define-->Boundary Conditions... panel.

Solve as an unsteady problem, and plot the average temperature in the main volume as a function of flow time (Solve-->Monitors-->Surface..)

thanks a lot, that worked. sivakumar