[vtkusers] Streamtube

[James C. Robinson]

Dear All,

I am using VTK for visualisation of an FE mesh and the transient potential
field (pressure/flow through porous media) occurring in the domain. In
addition, I have included flow field data (based on the pressure field and
the permeability) and I read this into a vtkUnstructuredGrid as a vector
data set.

I use a vtkStreamLine combined with a vtkPMTubeFilter to produce a
streamtube from any user nominated point in the domain. However, the utility
runs into problems sometimes. This manifests itself in that once the point
from which the streamtube is to be generated is chosen, the PC hangs while
it is trying to generate the streamtube. I assume it is because the flow at
the point (and around it) is so low that the integration process (back
through the flow field) has to take tiny steps. I could play with step
length, but if this is set very large one gets an inaccurate streamtube
path. I use a 2nd order runga kutta integrator.

Are there any procedures/approaches (or basic functionalities) that I could
employ to avoid this PC hang phenomenon. Is there a value (flow velocity)
below which I should not allow the stream tube to begin generating?

Any ideas would be welcome.

Jim


______________________

James C. Robinson, PhD,
Chartered Engineer,
42 Rivergrove,
Glanmire, Co. Cork,
Eire

Tel:         +353-21-4822028
Tel:         +353-87-2393010
Fax:        +353-21-4822721
E-mail:     jrobinson at eircom.net
______________________