The Proceedings of the Eighth International Conference on Creationism (2018)

seeking to reproduce the data as closely as possible employs a heat sink of the form shown in equation (14). The input parameter values are Δ t = 0.0005 year (~4.38 hours), τ hs = 0.005 year (~1.83 days), ʋ 0 = 0.22 ms -1 , τ ƒ = 0.25 year and τ d = 0.2 year (73 days). These values imply a maximum half spreading rate of 0.22 ms -1 and a total half-width of the ocean basin after 4,400 years of ~3,125 km (1,940 miles). In order to minimize mesh resolution problems related to the near- surface thermal boundary layer, we have: (1) used the finest mesh resolution available; (2) modified the initial temperature profile to give an initial boundary layer thickness comparable with the mesh size. We did this by assuming a profile corresponding to the solution of the textbook half space problem after a notional 100 years. This stratagem has no time implications: it is used solely for computational convenience. Its implications are considered further in the Discussion section below. We have also (3) removed any formal inclusion of the thermal boundary layer in surface heat flux calculations, which are now done purely on the basis of temperature values stored on the mesh. This is done in order to remove the artificial kink in the heat flux curve which is otherwise observed as the boundary layer weakens and thickens over time until the flux it predicts falls below that based on mesh temperatures. Because of these changes we have run the calculations with three different mesh resolutions, viz. Δ z = 190 m (i.e. 500 intervals through the plate), Δ z = 95 m (1000 intervals) and Δ z = 47.5 m (2000 intervals) and compared the results to check for mesh convergence. Although there are significant differences between these cases at early times, notably in the most sensitive output variable, viz. surface heat flux, they give very similar results for integrated quantities such as total heat loss and shrinkage. Table 2 lists the surface heat flux values for early times as output by the three calculations. Even in the most favourable case (defined by the input data given above) there are systematic conflicts with the observational data, most notably (1) the excessive surface heat fluxes seen at early times, i.e. in the central region of the ocean basin, and (2) the very rapid shrinkage seen close to the ridge; see Figure 9. The corresponding temperature profiles are shown in Figure 10. Although these features can be shifted by changing the time scales in the calculation, they are inevitably shifted together. For example, the calculated depth profile can be made fairly realistic by shrinking the spreading time scales to τ ƒ = 0.045 year and τ d = 0.09 year while ʋ 0 is increased to 0.733 ms -1 . The results are plotted in Figure 11: while the depth profile is fairly realistic the surface heat flux is excessive over almost the whole width of the ocean basin. DISCUSSION 1. Enhanced thermal conduction hypothesis The physical properties of a material are determined by the locations of atoms within a crystal or molecule, the strength of the bonds between the atoms and the arrangement of the crystals or molecules. We are interested in thermal conductivity – the ability to transfer thermal energy by diffusion. Non-metals conduct thermal energy by the vibration of one atom causing its neighbour to vibrate and so on. The stronger the bond the more rapidly the energy is transferred, but a stronger bond also results in a stiffer crystal. The outstanding example is diamond, whose crystals are extremely stiff and conduct thermal energy almost as well as metals. Worraker and Ward ◀ Ocean floor cooling ▶ 2018 ICC 680 Figure 8. Plot of surface heat flux against distance from the ridge axis in the case of a heat sink varying linearly with depth (maximum at the surface, zero at the bottom of the plate) and lasting just 0.025 year (9.13 days), while the period of rapid spreading (0.63 ms -1 ) lasts 0.2 year (73 days). Figure 9. Plots of surface heat flux and ocean depth against equivalent uniformitarian age for our ’final’ heat sink case. Reference curves based on the fitting equations given by Stein and Stein (1992) are included for comparison. The period of rapid spreading is 0.25 year (91.3 days), maximum speed 0.22 ms -1 .The results plotted here are based on the finest resolution mesh (Δ z = 47.5 m). Note that the depth profile is too narrow while the heat flux is excessive across a significant fraction of the basin width. Figure 10. Temperature profiles for the final heat sink case (Δ z = 47.5 m) in which the heat sink is proportional to the local temperature mismatch against the equilibrium state; at 4400 years the system is practically in equilibrium.