FIG. 7. Contour lines representing selected values (numbers on curves) of the dimensionless heat capacity kernel F*(X,Y,) for a dual-probe heat-pulse sensor with heater probe at (X,Y) = (–,0) and temperature probe at (X,Y) = (,0). The dots show the location of the probes. The exact values (solid lines) are from Eq. [34] and are identical to the contours for F*(X,Y,) = –0.0001, –0.001, –0.005, –0.02, and –0.04 in Fig. 6. The dashed lines are ellipses, which are approximations of the exact contours.