This paper presents a numerical simulation study on a disc pump in two different model scenarios of its connecting column region. The performance and the change in the flow inside the impeller under different flow conditions are examined and the calculations are verified with experimental measurements. Comparison of the calculations in the two schemes shows that in Scheme I

a significant low velocity region occurs on both sides of the connecting column

while in Scheme II

the local velocity is higher due to the set-up of near wall fluid. In the two schemes

local low-pressure areas occur on the blade suction surface

and the formed vortices also result in an increase in local energy dissipation. Therefore

most of the turbulent energy dissipation in the pump is concentrated on the blade suction surface

while energy dissipation near the pump inlet and outlet are weak. After the flow passes through the connecting column

its circumferential velocity and the circumferential component of its absolute velocity in Scheme II are smaller than those in Scheme I. This indicates that in pump operation

the energy loss generated by the blocking effect of the connecting column on the outlet flow is greater than the amount of energy brought by the column itself

resulting in a lift head lower in Scheme II than Scheme I. The calculations of the two schemes agree with the trends measured in the experiment

and the performance differences between them are rather small. Schemes I is simpler and efficient if only the rapid calculation of pump performance is considered; Scheme II is preferred if comprehensive and accurate information of internal flow is needed.