A `circular' bubble, of radius 32 grid points, was initialised at the centre of a 128 by 128 grid. The fluid density was set at everywhere with inside the bubble and elsewhere. The fluids were then allowed to evolve for 10,000 time-steps. The density and the order parameter were measured along a line through the centre of the inner fluid parallel to the y-axis (perpendicular to ) and are shown in figures 4-3 and 4-4 respectively at selected times.
Figure 4-3: The density as a function of r the distance
from the edge of the grid. The density is plotted
along a line through the centre of the inner
fluid parallel to the y-axis (perpendicular to .
Figure 4-4: The order parameter plotted against
r the distance
from the edge of the grid. The order parameter is plotted
along a line through the centre of the inner
fluid parallel to the y-axis (perpendicular to .
The relaxation times used were and . The relaxation time is which is the value at which the model is Galilean invariant [9, 38]. This initialisation differs from the final state in four ways. The order parameter has changed from its initial value of to its expected value of 0.50. The initially interface width of one lattice unit has increased to about ten lattice units. The shape of the inner fluid has changed from an ellipse with semi-major and semi-minor axis of 32 lu and lu to a circle with radius lu. The final density is slightly larger in the inner fluid than the outer fluid. The small change in the density occurs everywhere within the first 1,000 time-steps with only a small change in the shape of the interface occurring at subsequent times. The larger change in the order parameter takes 10,000 time-steps to reach the areas furthest from the interface. The movement of the inner fluid from an ellipse to a circle is achieved within the 10,000 time steps.