CALCULATION OF ALL DRAG COMPONENTS FOR 3-D BODIES IN WIND-TUNNEL FLOWS - A BOUNDARY ELEMENT-WAKE APPROACH

A boundary element-wake numerical approach is developed and used to de termine all drag components of a three dimensional body in a wind tunn el flow. The approach decomposes the total drag into three components; the profile drag, the cross flow drag (induced drag), and the tunnel- wall effect component, each with its own physical significance. Additi onally, the cross flow drag component is divided into two components, the vortex component and the source (dilatation) component. In the pre sent approach, the transverse kinematics relations are expressed as in tegral representations of the axial vorticity and the transverse dilat ation (source strength). This advantage permits the vortex and the sou rce drag computations to be performed only in the vortical area of the transverse wake and hence avoids excessive computations. Also, the pr ocedures distinguish the contribution of the transverse dilatation to the cross flow drag. The validity of the present procedure is examined by comparing the present results against the experimental data of ref erence [1] for a car and wing models. The comparison shows that the pr esent computed total drag, for the wing and the car models, agrees ver y well with the experimental data, provided that the wake data are mea sured at survey planes moderately distant from the body.