initially implemented into a script file to approximate a parabolic pressure flow
distribution by applying individual forces to nodes. Forces are determined from the
product of the local pressure and the projected area around the node. Figure 4.7 shows a
representative projected area for one node. Applying the pressure distribution to the
tension-only membrane tube in this manner yielded numeric instability. This numeric
instability and a need for only global effects of the drag leads to the assumption that local
pressure effects of the flow on the tube can be neglected. This simplifies the model by
approximating the total drag as an equally distributed load. Figure 4.8 shows an example
of the total drag force divided equally and applied to all the nodes along the length of a
typical tube. All nodal drag forces are applied in the same global coordinate direction.
Xi-1 Xi Xi+1
Figure 4.7 Representative projected area around one surface node