Looking at the source code IllinoisGRMHD in the ET seems to support piecewise polytropic EOS, at the very least for a single piece by setting up IllinoisGRMHD’s
gamma_th parameter and the first entry in the
eos_params_arrays2 grid array (eg by setting ID_converter_ILGRMHD’s
Initial_K parameters). However D_converter_ILGRMHD contains an explicit check for a simple Gamma-law (ie no difference between thermal and cold Gamma) in
// P = (\Gamma - 1) rho epsilon // -> \Gamma = P/(rho epsilon) + 1 double measured_gamma = ( P[index]/(rho_b[index] * eps[index]) + 1.0 ); if(rho_b[index]>rho_b_atm && fabs(gamma_th - measured_gamma)/gamma_th > 1e-2) CCTK_VError(VERR_DEF_PARAMS, "Expected simple gamma law with gamma_th=%.15e, but found a point with gamma law such that gamma_th=%.15e. error = %e| rb=%e rbatm=%e P=%e\n", gamma_th,measured_gamma,(gamma_th-measured_gamma)/gamma_th,rho_b[index],rho_b_atm,P[index] );
There is also no documentation (at all as far as I can tell) on what EOS IllinoisGRMHD supports or how one would go about setting them up.