This test suite case models a conductively-propagated deflagration wave (“flame”) in a high-density, degenerate carbon-oxygen mixture. It is similar to a calculation presented by Timmes & Woosley (1992).
Careful modeling of the flame speed requires a much larger nuclear network than the 21 isotope network used in this test. Timmes & Woosley (1992) use a 130 isotope network, Chamulak et al. (2007) use a 430 isotope network, and Schwab et al. (2020) use a 495 isotope network.
Unlike most MESA calculations, this models a small sphere of material
(instead of an entire star). The initial model is built in
run_star_extras using the
other_build_initial_model hook. A
spatially uniform model with a given density, temperature, and
composition is constructed. A small hot spot is then added at the
center of the model. The properties of this initial model can be
controlled from the inlist.
use_other_build_initial_model = .true. x_integer_ctrl(1) = 300 ! number of points x_ctrl(1) = 10 ! mass (in g) x_ctrl(2) = 1d10 ! initial density (cgs) x_ctrl(3) = 2d8 ! initial temperature (cgs) x_ctrl(4) = 0.0001 ! size (in q) of region to heat x_ctrl(5) = 5d9 ! temperature of that region x_ctrl(6) = 0.50 ! mass fraction c12 x_ctrl(7) = 0.50 ! mass fraction o16
The inner boundary is at r = 0. The outer boundary has a fixed
temperature and a fixed pressure equal to the initial pressure of the
material. This is achieved via the
After an initial transient, the entire flame structure, approximately isobaric, propagates into the upstream fuel with a unique speed and width. The test succeeds if the flame successfully propagates through half of the domain and reports values for the flame width and speed that are within 10% of the specified reference values (see inlist). The flame width and speed are reported to the TestHub.
The flame speed is measured using the time/position when the flame is
30% of the way through the domain and time/position at the end of the
test. The flame width is measured at the end of the test as the width
eps_nuc is greater than 10% of its peak value. See
flame_properties in the
Last-Updated: 2021-06-21 (mesa b2364463) by Josiah Schwab