[Mesa-users] convergence problem

[sheyda najafi]

Dear Mesa users

I have another question regarding my previous emails.

As i  said I wanted to study the evolution of 1 solar mass star in the
presence of
new extra acceleration term :(-beta*(clight**2)*(dphi/dr)).
 i have changed the
extra_dPdm subroutine of MESA code to add
the extra term (-beta*rho(clight**2)*(dphi/dm)) ==>( in lagrangian framework) .
 where phi depends on local density of each layer(cell density: s% rho).
 which is named (xn) in the code. and beta is a constant.
i have added the extra term as follows

           do k = 1,2
             s% extra_dPdm(k) = -( ((   xn(k)-    xn(k+1))/(s%
dm_bar(k+1)))*((beta*(clight**(2.0d0)))*(s% rho_face(k))) )

         end do

         do k = 2, s% nz-1
          s% extra_dPdm(k) = -( (((   xn(k)-    xn(k+1))/(s% dm_bar(k+1)))+ &
         ((   xn(k-1) -   xn(k))/(s% dm_bar(k))))
*((beta*(clight**(2.0d0)))*(s% rho_face(k))*(1.d0/2.d0)) )

         end do

         do k = s% nz-1, s% nz
          s% extra_dPdm(k) = -( ((   xn(k-1) -    xn(k))/(s%
dm_bar(k)))*((beta*(clight**(2.0d0)))*(s% rho_face(k))) )

        end do

I noticed that  s% dm_bar(s%nz) = s%dm(s% nz) + s%dm(s%nz-1)/2
and not (s% dm(s% nz) + s% dm(s%nz-1))/2.

i am not sure that dm_bar must be used in extra_dpdm or  (s% dm(s% nz)
+ s% dm(s%nz-1))/2.

Thank you very much
Sheyda Najafi


On 10/21/18, sheyda najafi <sh.najafi8590 at gmail.com> wrote:
> Dear Josiah and MESA users
>
>
> I have another question regarding my previous emails. i have asked it
> before but unfortunately no one answered.
>
> As i  said I wanted to study the evolution of 1 solar mass star in the
> presence of
> new extra acceleration term :(-beta*(clight**2)*(dphi/dr)).
>  i have changed the
> extra_dPdm subroutine of MESA code to add
> the extra term (-beta*rho(clight**2)*(dphi/dm)) ==>( in lagrangian
> framework) .
>  where phi depends on local density of each layer(cell density: s% rho).
>  which is named (xn) in the code. and beta is a constant.
>
>            do k = 1,2
>              s% extra_dPdm(k) = -( ((   xn(k)-    xn(k+1))/(s%
> dm_bar(k+1)))*((beta*(clight**(2.0d0)))*(s% rho_face(k))) )
>
>          end do
>
>          do k = 2, s% nz-1
>           s% extra_dPdm(k) = -( (((   xn(k)-    xn(k+1))/(s% dm_bar(k+1)))+
> &
>          ((   xn(k-1) -   xn(k))/(s% dm_bar(k))))
> *((beta*(clight**(2.0d0)))*(s% rho_face(k))*(1.d0/2.d0)) )
>
>          end do
>
>          do k = s% nz-1, s% nz
>           s% extra_dPdm(k) = -( ((   xn(k-1) -    xn(k))/(s%
> dm_bar(k)))*((beta*(clight**(2.0d0)))*(s% rho_face(k))) )
>
>         end do
>
> Since i did not know the value of s%rho(0) i did'nt have xn(0) to
> write extra_dpdm it in 1 part therefore i have split it in three
> parts. how it is possible to write this term in 1 part. i mean if i
> want to write the extra term as :
>
>          do k = 1, s% nz
> s% extra_dpdm(k)= -((   xn(k-1)-    xn(k)) / s% dm_bar(k)) * beta*
> (clight**2)* ( s%rho_face(k)).
>         end do
>
> I will have problem in finding the value of xn(0). because xn is
> related to cell density s%rho(0) via
>
>    xn(i)= (( n1*(lambda**(4.d0+n1)) )/(((mpl)**(n1))*clight*beta*s%
> rho(i)))**(1.d0/(n1+1.d0))
>
> lambda, mpl, n1 and beta are constant.
>
>  which density should i use as rho(0) ??
>
> (for your kindly information my codes are attached in the email)
> Thank you in advance
>
>
> Sheyda
>