Deformations of a polymer fixed at one end and subjected to a uniform flow are investigated with special emphasis on the hydrodynamic interaction (HI) between polymer segments. The so-called non-draining effect, which results from the collective hydrodynamic back-flow caused by all segments, is calculated for the first time with fluctuating hydrodynamic interactions. HI reduces the viscous drag and the flow partially penetrates the polymer coil. Therefore neither the free-draining nor the non-draining models discussed previously describe the polymer-flow interaction appropriately. Accordingly the f-shell blob model is introduced, describing the partial draining and the transition to a free-draining polymer with increasing flow velocity, similarly as in simulations.