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--- examples_aswns_kepler [2022/08/16 13:27]
theoastro [Changing the code input]
+++ examples_aswns_kepler [2022/08/16 22:02] (current)
theoastro [Plotting your results]
@@ Line 1: / Line 1: @@
 ===== Computing stars at the Kepler limit =====
-This test follows the computation performed in [[https://arxiv.org/pdf/1908.11258.pdf|Camelio et al., 2019]]. While the code is not perfectly identical to the one used for the paper, the code changes have been minimal.
+It is worth pointing out that this test case takes up more runtime than the other that is provided for the computation of the [[examples_aswns_nonbaro|non-barotropic configuration]], hence, it might be useful to check out this test first if you have not done so.
-==== Model Parameters ====
+==== Theoretical Background and Input Parameters ====
-==== Theoretical Background ====
+In this setup, we consider a cold rigidly rotating neutron star described by an equation of state (EOS) of the form:
-For a careful theoretical understanding, one has to investigate the exact model parameters that are employed. The equation of state follows the form  (Eq. 45 of [[https://arxiv.org/pdf/1908.11258.pdf|Camelio et al., 2019]]):
+{{ASWNS_EOS_5.png|EOS5}}
-{{ASWNS_EOS_1.png|EOS1}}
+with the free parameters k1 and Gamma.
-with the thermal barotropic law
+The potential Q follows the form (Eq. 38 of [[https://arxiv.org/pdf/1908.11258.pdf|Camelio et al., 2019]])
-{{ASWNS_EOS_2.png|EOS2}}
-and the rotational barotropic law (Eq. 24 of [[https://arxiv.org/pdf/1908.11258.pdf|Camelio et al., 2019]])
-{{ASWNS_EOS_3.png|EOS3}}
-with  (Eq. 38 of [[https://arxiv.org/pdf/1908.11258.pdf|Camelio et al., 2019]])
 {{ASWNS_EOS_4.png|EOS4}}
-==== Changing the code input  ====
 The simple example that is given in the git repository looks at a cold, rigidly rotating neutron star.
 In input parameters can be found at the beginning of kepler.f90 and they are:
- * gam (double) --> polytropic index of the cold component
+  * **gam** (double) --> polytropic index of the cold component
- * gamth (double) --> exponent of the thermal component
+  * **k1** (double) -->  proportionality constant of the cold component
- * k1 (double) -->  proportionality constant of the cold component
+  * **omg0** (double) --> angular velocity (rigid rotation)
- k2 (double) --> proportionality constant of the thermal component
+  * **rhostart** (double) --> starting density of the Keplerian curve
- k3 (double)     -->  entropy proportionality constant of the barotropic law
+  * **rhoend** (double) --> final density for the search, e.g., 7d0*rhon
- omg0 (double) --> angular velocity in the center
+  * **verbose** (logical parameters) -->  determines is output is put on the screen
- bvalue (double) --> baroclinic parameter
+  * **filename** (character) --> defines where to store the results
- rho0 (double) --> central rest mass density
- sigma (double) --> inverse scale radius of the differential rotation sigma = 1/R0
- verbose (logical parameters) -->  determines is output is put on the screen
- logfile (character) --> defines where the extended summary of the results is stored
- binfile (character) --> defined where the stellar profiles are stored
- maxit (integer) --> maximum number of iterations for the Newton-Raphson scheme
- tol (double) --> relative tolerance of the employed Newton-Raphson scheme
-   relax_iters (integer) --> relaxation iterations in the force balance equation (Euler) solver
-  rhocit (double) --> critical density for the EOS inversion from (p, hden) to (rho, s)
-  funmax (double) --> maximal value of the function needed for the EOS inversion from (p, hden) to (rho, s)
 ==== A first Test ====
-After following the outlined [[installation_ASWNS|installation guide]], you can run a first test configuration
+After following the outlined [[installation_ASWNS|installation guide]], you can run a first test configuration,  but it might be worth reducing the resolution (see [[general_aswns|the discussion about the general settings]] to know how to do this).
+Please remember that, in case you change the grid spacing in ASWNS.f90, you have to recompile the code, afterwards you can run it with
   ./kepler.x
@@ Line 79: / Line 62: @@
    error flag           =            0
-This was simply the first step of the iteration and you see that the code is continuously increasing the mass and tries to find the maximum mass that you can reach at the Kepler limit. For this dummy example, you should arrive at:
+This was simply the first step of the iteration, and you see that the code is continuously increasing the mass and trying to find the maximum mass that you can reach the Kepler limit.
+The final results will be written in the file that you provided, by default this would be kepler.dat. The individual columns refer to:
+     * the central density
+    * axial Omega
+    * the corresponding error flag (0 means no error)
+    * the gravitational mass in Msun
+    * the baryonic mass in Msun
+    * the proper mass
+    * total stellar entropy,
+    * the angular momentum
+    * the rotational energy
+    * the equatorial omega,
+    * the Keplerian Omega
+    *  the equatorial radius in Msun,
+    * the equatorial radius in km
+    *  radius at the pole in Msun
+    *  the disk mass
+    * the derivative dm/drho
+==== Plotting your results ====
-This computation can take a while, so please be patient.
+Based on the result in kepler.dat, you could check your results. One straight forward way would be to look at m(rho) and plot this with gnuplot, e.g.,
+gnuplot
+gnuplot> plot 'kepler.dat' u 1:4 w l
-==== Plotting your results ====
+which gives you the following plot of the gravitational mass as a function of the central density.
+{{aswns_kepler_simple.png}}

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