For most multiphase flows it is more appropriate to evaluate the total pressure from the static pressure obtained from p_rgh rather than from p_rgh directly.
Reference: Duisburg Test Case (DTC) el Moctar, O., Shigunov, V., Zorn, T., Duisburg Test Case: Post-Panamax Container Ship for Benchmarking, Journal of Ship Technology Research, Vol.59, No.3, pp. 50-65, 2012