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efficient parallel computation to simulate blood flow - CiteSeerX

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The NS equations simplify then in<strong>to</strong> the S<strong>to</strong>kes equation in the neighborhood of<br />

the inlet and outlet of the fluid domain Ω f . To avoid reflection of acoustic waves at<br />

the outlet one may then use transparent boundary conditions [19].<br />

On the horizontal wall we assume either the periodicity of all variables, or we<br />

impose the <strong>flow</strong> speed <strong>to</strong> be U w .<br />

Further improvement in the grid discretization implementation may use a high<br />

order interpolation scheme for the convective term that introduces less dissipation<br />

and a mesh refinement in the neighborhood of the interface Sw.<br />

f<br />

We have all the information <strong>to</strong> solve the NS equations. The main goal of this<br />

project is <strong>to</strong> get the fastest results. A short <strong>computation</strong> time <strong>to</strong> obtain a solution<br />

of the NS equation requires an <strong>efficient</strong> solver.<br />

3.3 Aitken Schwarz 3D<br />

For solving the linear system, our solver uses also the Aitken-Schwarz Domain decomposition<br />

technique presented in Chapter 2 for a two dimensional case. The main<br />

difference between the two and three dimensional simulation is that the Fourier decomposition<br />

and the subdomain solver solve only a tridiagonal problem.<br />

The domain Ω = (0, Lx) × (0, Ly) × (0, Lz) is decomposed in<strong>to</strong> q overlapping<br />

strips Ω i = (X i l , Xi r ) × (0, Ly) × (0, Lz) with X2 l < X 1 r < X3 l < X 2 r , ..., Xq l<br />

< X q−1<br />

r<br />

as<br />

described in Figure 3.4<br />

The pressure unknown is developed in<strong>to</strong> the sine expansion in<strong>to</strong> the physical space<br />

79

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