The GCG solver dialog appears as follows. A common dialog structure is applied in both the transient and steady state solutions. Depending on the solution requested, the buttons and information associated with transient solutions are grayed out. As indicated, there are 5 primary framed areas on the dialog to assist the user in setting up the solver.
Hyperion-GCG
ITR Stalling
For a discussion on why iterative methods stall in solution, review the following notes from the CTA course
GCG Feature List (abbreviated)
• Compiled as EXE and DLL with general API (Application Program Interface)
• Several preconditioners, Unity, Jacobi and SOR
• Control for nonlinear coefficient matrices such as radiation or array dependencies
• SmartConfigure to setup dialog depending on the node and conductor type
Hyperion-GCG is a general-utility semi-direct solver. GCG stands for Generalized Conjugate Gradient. GCG is a semi-direct-inversion solver capable of producing ultra-fast solutions to thermal diffusion and advection problems. Hyperion-GCG is not the typical conjugate gradient solver. In fact, this GCG solver can turn over and solve for advection problems and nonlinear thermal matricies which are introduced with array-dependent or radiation conductors. This is the direct result of tuning the conventional CG algorithms to handle these special add-ons in CHT modelling.
Speed Test
Benchmark Test The following problem is offered as a benchmark test. The following images show how to setup the geometry and boundary conditions. The NASTRAN bulk data file is available for download to allow the geometry to be reconstructed rapidly. This problem is solved in 0.15 seconds using GCG (SOR preconditioner 5 subiterations). In contrast, the TAS solver with SOR factor 1.95 solves in about 10 seconds. Tests were performed with a Pentium ® P4 3.0 GHz system.
Geometry
BCs and Source
Results
The GCG solver can be compiled to either a stand-alone EXE or a DLL which can linked into your project. As an example of the success of the DLL usage, Ansys employs the GCG-DLL in both the Ansys-TAS and Ansys-Icechip modules.
One of the unique and proprietary features of GCG is the SOR preconditioner. With the SOR preconditioner, you can actually solve a thermal problem, which may have taken 10,000 iterations, in as few as 20 iterations. GCG offers an incredible speed boost over convention relaxation thermal solvers. Hyperion-GCG has been clocked to be over 100 times faster than conventional SOR solvers. Note that speed differences can vary widely between thermal problems.
