Figure 9.

CFD results for R. triqueter at a 20° pitch angle. The graphs show pressure on the boxfish carapace surface (a; top = lateral view, bottom = frontal view), iso-moment contours as a function of pitch axis position (b) and pitch 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. Note that the neutral position of the pitch axis (zero moment; bold line) lies considerably anterior of the centre of mass (b), so that a destabilizing moment occurs for rotation about a pitch axis through the centre of mass.