OpenLB – Open Source Lattice Boltzmann Code Forums on OpenLB General Topics Poiseuille 3D Geometry Creation Query

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• #5956
achodankar
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Hello Developers,
I would like to understand the concept of why the inlet and outlet is set to a number of crossections. The inlet is set from from -2 deltax to 2 deltax, similarly the outlet is set from length – 2 deltax to length + 2 deltax. Why not just set the first cross-section to inlet and the last cross-section for the outlet.

For example in the code:

superGeometry.rename(0, 2);

superGeometry.rename(2, 1, pipe);

if (flowType == nonForced)
{
Vector<T, 3> extend = origin;

// Set material number for inflow
origin = -converter.getPhysDeltaX() * 2;
extend = converter.getPhysDeltaX() * 2;
superGeometry.rename(2, 3, 1, inflow);

// Set material number for outflow
origin = length – 2 * converter.getPhysDeltaX();
extend = length + 2 * converter.getPhysDeltaX();
superGeometry.rename(2, 4, 1, outflow);
}

The second question, Can you explain the concept behind the following code?

IndicatorLayer3D<T> extendedDomain(pipe, converter.getPhysDeltaX());

I don’t undersatnd the extended domain part.

Lastly, after creating and initializing the lattice, why do we extend the center to -0.2 deltax? The geometry creation and application of boundaries is a bit confusing for me in the Poiseuille 3D case.

IndicatorLayer3D<T> indicatorExtended (pipeExtended, 0.9*converter.getConversionFactorLength()*N/11.);

I would really appreciate any explanation on these questions. It would be of great help to me.

Thank you.

Yours sincerely,

Abhijeet C.

#5960