Engineering topics

Pretsch, J

Publications and source records attributed to Pretsch, J.

2 records

NASA NTRS1942

The stability of laminar flow past a sphere

As a contribution to the problem of turbulence on a surface of rotation, the method of small oscillation is applied to the flow past a sphere. It was found that the method developed for two-dimensional flow is applicable without modifications. The frictional layer in the vicinity of the stagnation point of a surface of rotation is less stable against small two-dimensional disturbances than in the stagnation point itself, as proved from an analysis of the velocity distribution made by Homann.

Pretsch, J↗

NASA NTRS1942

Theoretical solution of profile drag

After a survey of the customary procedures for appraising the profile drag in which pressure drag was discounted and the methods for computing the laminar and turbulent friction flow, the author proposes a method by which the pressure drag can be computed with the aid of the displacement thickness of the frictional layer. The method is restricted to the case where the effects, caused by separation of frictional layer, are small. Then the total profile drag can be expressed solely by quantities derived from the velocity distribution in the frictional layer immediately at the trailing edge.

Pretsch, J↗