can alternate combustion model by UDF?
 

I'm trying to use PDF turbulence combustion model to simulate supersonic combustion. But it seems that this model has difficulty in convergence. Personally i think it may result from that the averaged field is obtained by statistic average. In shock regions, parameters have great gradient, statistic method may lead to too much statistical discrepancy. Then i want to alternate the combustion model during calculations. In this step, combustion model is PDF, and then in the next few steps, it will be chaged to other combustion models (EDC for example), and then it is changed to PDF again, so repeatedly. use the smooth flow field of EDC to enhance the convergence of PDF combustion model. can this idea be achieved by UDF? Wish someone can help me or exchange ideas with me, thanks a lot!

Han Xingsi