Page 184 - Wind Energy Handbook

158 AERODYNAMICS OF HORIZONTAL-AXIS WIND TURBINES

Figure A3.3 Inviscid Flow Pressure Distribution Around a Cylinder

In a real fluid, when the viscosity is low and the velocity is relatively high, the
drag force that exists is due primarily to an asymmetric pressure distribution, fore
and aft (Figure A3.5). This is caused by the fact that the fluid does not follow the
boundary of the body but separates from it leaving low pressure, stagnant fluid in
the wake (Figure A3.4). On the upstream side the flow remains attached and the
pressure is high.

Figure A3.4 Separated Flow Pattern Around a Cylinder