gas-liquid upflow and downflow in packed bed ,the Ergun pressure drop is same?
 

hello :
i want to simulate the gas-liquid upflow through the packed bed ,In the literature i can find Ergun pressure drop ,but i can not find the Ergun pressure drop formula about upflow through porous media
i want to know :the Ergun pressure drop formula is the same in gas-liquid upflow and downflow in packed bed ???
thanks