* New 3D version allows design and computation within a three-dimensional mesh as well as with a 2D-mesh of previously released versions. Heat3D can also generate movie files (avi) from its Playback window. With version 4.09, multithreading of Heat3D is increased to provide parallel processing on computers with hyper-threading and/or multiple processors.
Built around solution of conservation of energy by finite differencing, HEAT is a user interface that allows design of a computational mesh representing rock geometry, properties, and magma body emplacement. The following text gives some more background.
The original version of HEAT was a FORTRAN program described in the book "Volcanology and Geothermal Energy" by K. Wohletz and G. Heiken (University of California Press, 1991, 432 pages). Generally following the solution scheme described in Appendix E of that book, this HEAT version includes a number of improvements.
HEAT is a graphically interfaced application written for a PC running Microsoft WindowsTM. Designed to study 2-D and 3-D transient thermal regimes in and around magmatic intrusions, HEAT models a variety of geologic structures and rock properties and their effect on both conductive and convective heat flow. The graphical interface is readily used to develop and tailor the simulation to represent most geological conditions of magma intrusion and geological structure. Calculated thermal regimes are color encoded and updated in graphical display with each update stored as a file for future playback. This modeling goes well beyond that done by analytical solution of 1-D linearized expressions of thermal diffusion in that it calculates the nonlinear effects of heterogeneous media, temporal, spatial, and thermally varying properties, latent and radioactive decay heat, and magma convective heat transfer. As with most geophysical modeling, the results of these calculations are not mathematically unique for inversion applications. However, rigorous application of geological constraints afforded by this code can greatly reduce the number of simulations that might satisfactorily fit observations.
The following equation is solved:
where T = temperature, t = time, k = thermal diffusivity, and u = the buoyancy-driven convective velocity, and q = heat source/sinks (such as latent and radioactive decay heats). The first term on the right-hand-side represents heat conduction, the second convection heat flow, and the third term represents heat source/sinks of the latent heat of crystallization/fusion and radioactive decay.
HEAT employs an explicit finite differencing scheme rather than an alternating direction implicit one in order to insure that the original differential equation solved is exactly reproduced by the finite difference equation when time and spatial steps are infinitesimal. Truncation errors that might evolve when using very short time steps are minimized by utilizing double precision. Continuous thermal gradients are assigned along the boundaries where symmetry planes are not specified, and initial conditions use a designated regional thermal gradient. Latent heats of fusion/crystallization are solved for all rocks including magma where temperatures are in that range. New magmas may be introduced into the calculational mesh at any time during the simulation with or without the calculation of heat advection caused by rock displacement necessary to make space for the magma. All rock/magma properties are assigned by the user and they include: density, porosity (fluid saturation), heat capacity, initial temperature, spatially and thermally varying thermal conductivities, and location. As mentioned earlier, the code has been applied to several geologic areas to test its suitability. A version of heat has been adapted for laboratory rock melting experiments involving thermal variations of rocks melted by a moving hot molybdenum probe. Results thus far have shown the method predicts measured temperatures with enough accuracy to make engineering designs based on it. More documentation can be viewed in the file HEAT3D.pdf.
An excerpt of recent work on the Campi Flegrei caldera thermal evolution demonstrates some of our ongoing application of HEAT. This work builds on earlier applications in study of the Clear Lake volcanic field in California.
An example screen (below) shows the mesh-design window for HEAT in which rocks are assigned grid locations, properties, and conductive/convective values. The mesh can be updated anytime during the calculation to accommodate structural changes and injections of new magma. For 3D design, a popup window is displayed in which the user can edit the mesh in the third dimension.
The follow screen picture shows the thermal map for a specified time of calculation generated by HEAT. Since each thermal map is saved during the calculation, the calculated thermal history can be played back as an animation at different speeds as shown. Various other plots can be generated, for example thermal profiles at specified times and locations.
KWare Heat3D software (LA-CC 99-27; Copyright © 1999 UC) is available as self-installing files for downloading for 32-Bit Windows operating systems.
Download for Windows 9x/ME/NT4/2000/XP/Vista: Heat3D_Install (version 4.11.0533, ~4.5 MB, 10 July, 2008)
When using this program remember the old adage of "garbage in, garbage out!"
DISCLAIMER: The development of these programs was sponsored by the United States Government. Neither the United States Government, nor the United States Department of Energy, nor the University of California, nor any of their employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. References herein to any specific commercial product, process, or service by trade name, mark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.