Dear friends i did cfd analysis for centrifugal pump, and for max flow to design point(operating point) flow range cfd head is acceptable with experimental head, but for the flow below design point cfd head is decreasing & it is less for low flow rate, but theorotically head should be higher at low flow rate Can anyone please guide me resons behind this????

Thank You Nitin Suryawanshi

how it is possible? as i know (correct me if i am wrong) for low head mass flow rate is higher, and for higher head mass flow rate is lower.