Core critical gradient test case

This test case will exercise the core component in FACETS on a single field, conservation equation involving a highly nonlinear flux which is zero below some critical field value and large above. Starting with a parabolic profile, the critical transition point will cascade leftwards as the profile relaxes to approach the marginal critical profile. The test case shows the negative effect of resolution in reducing the ability to find a nonlinear solution, which is partly cured by applying a multigrid approach. More about this case at  http://www.txcorp.com/~pletzer/FacetsCritGradient.html.

Core GLF23 test case

This test case exercises the GLF23 code, which is used to compute the fluxes of plasma density, ion temperature, and electron temperature. The initial, parabolic profiles for n, Te, Ti were chosen so as to have unstable ITG/ETG modes over a large section of the core plasma. A sharp profile slope discontinuity depvelops and moves towards the center while the Ti profile develops a pedestal at the edge. It is a test case that illustrates the difficulty in evolving a conservation law with highly nonlinear fluxes. More about this case at  http://www.txcorp.com/~pletzer/FacetsGlf23.html.