CFD Online Discussion Forums

CFD Online Discussion Forums (
-   CFX (
-   -   Semi-batch process (

Jonac October 17, 2000 23:01

Semi-batch process
CFX Users

A semi-batch system is of continuous input but no output. Say a gas liquid/solid system with weakly compressible flow specified to the gaseous fluid, then how to set up the no output of the system without upsetting the mass balance in CFX?

Any comment is welcome and much appreciated.


Gert-Jan van der Gulik October 18, 2000 06:51

Re: Semi-batch process
I am not sure if you can solve such a problem without making simplifications or using some Fortran-tricks.

Therefore: What is of interest in your simulation i.e. what is the problem you want to solve? Are you interested in the flow of the liquid or feed mixing? Or are you interested in the flow of the gas? Or perhaps both?

Regards, Gert-Jan

Jonac October 22, 2000 19:56

Re: Semi-batch process

The problem will be focussed on inter-phase mass transfer between gas and liquid followed by chemical reaction in an agitated vessel.

Could you elaborate the possible simplification can be carried out, please?


Gert-Jan van der Gulik October 23, 2000 03:22

Re: Semi-batch process

I guess you have a vertical vessel to which gas is fed at the bottom through some gas inlet. Then why do you want to leave out the gasoutlet (i.e. leaving out the degassing boundary in CFX 4.3). Is the obtained pressure increase really that important for the process under study?


Jonac November 8, 2000 21:06

Re: Semi-batch process

We have solved the problem for now by specifying inlet as pressure boundary condition and no outlet in the system physically. The reason for preserving the semi-batch feature is because the gradual accumulation of the gas pressure in the head space of a vessel directly influences the solubility of the gas reactant in the reaction mixture and hence the reaction rate.


Gert-Jan van der Gulik November 10, 2000 05:23

Re: Semi-batch process

Such a problem is hard to simplify and this looks a good approach. Good luck.


All times are GMT -4. The time now is 04:03.