Hi,

I'm doing a Flotran analysis and I have to model a cooler (for electric machines) with an air filter.The distributed resistance must be specified for the filter and I have the measured (pressure drop) vs (outlet velocity) diagram for the filter.How can I find from that the a and b coefficients for the friction factor f=a*(RE)**(-b)!? (From Darcy-Weisbach equation is possible to find the friction coefficient,but what is the hydraulic diameter and Reynolds-nr. in case of filters?) Has somebody experience using this method of specifying the distributed resistance?

Regards, Zoltan

Trying is the best way. Change the parameter as long as the required pressure loss over the filter element is achieved.