Figure 7.

CFD results for O. cubicus at a 20° yaw angle. The graphs show pressure on the boxfish carapace surface (a; top = dorsal view, bottom = frontal view), iso-moment contours as a function of yaw axis position (b) and yaw moment on separate patches of the carapace surface (c). The position of the centre of mass (assuming homogeneous material density inside the carapace) is indicated on the iso-moment contour graph. Similar to R. triqueter (figure 6), the neutral position of the yaw axis (zero moment; bold line) lies considerably anterior of the centre of mass (b), so that a destabilizing moment occurs for rotation about a yaw axis through the centre of mass.