Case Studies of the Human Cardiovascular System - Computational Hemodynamics: Theory, Modelling and Applications - page 230

Fig. 7.37 Volume change of the atrial cavity measured from MR recordings throughout diastole

The atrium was kept fixed during the simulation. However, the measured venous
mass flow rates do not account for the extra mass flow exiting the atrium due to atri-
al contraction throughout diastole. The additional flow due to atrial volume change
was calculated from the segmented atrial geometry and evenly distributed among
the four venous flow inlets. The change in atrial volume during diastole is illustrated
in Fig. 7.37 . A no-slip condition was imposed at the walls.

7.6.3 Results

7.6.3.1 Intra-Atrial Flow Pattern in Model- C A

Figure 7.38 shows flow entering the right atrium chamber through streamlines for
each pulmonary vessel and the velocity distribution at the mitral orifice at t = 100 ms,
relative to the beginning of diastole. The flow field is presented by streamlines to
provide an instantaneous image of the flow field by using information from a single
time frame. For the (a) right inferior pulmonary vein the streamlines enters the left
atrium near its septal side and the streamlines follow the smooth contour of the atrial
wall towards the septal/inferior side of the mitral plane. The jet is deflected by the
second jet from the left inferior pulmonary vein, but these two jets do not interfere
at this stage. The streamlines originating in the (b) right superior pulmonary vein
behave in a similar manner but enter the mitral valve at the septal/superior side. The
outer, most superior, part of the right superior pulmonary vein inflow, is disturbed