[Mesa-users] convergence problem
sheyda najafi
sh.najafi8590 at gmail.com
Tue May 14 09:57:01 EDT 2019
Dear Pablo
Thank you very much.
I thought that by adding the new acceleration as extra_dpdm in HSE
equation of MESA code, other equations which depend on acceleration,
change due to gravitational force + extra force.
1)So there is no relation that relates grav to extra_dpdm or dlnp_dm_qhse?
2)what might happen to the star if I add extra_dpdm to HSE equation
and do not change pressure_scale_height?
3)Do you think it would have impact on stability of the star?
Thank you
Sheyda
On 5/14/19, Pablo Marchant <pamarca at gmail.com> wrote:
> Hi Sheyda,
>
> The pressure scale height is set in star/private/mlt_info.f90, assuming
> standard hydrostatic equilibrium, so its set as
>
> scale_height = P / (grav*rho)
>
> If you want to modify the pressure scale height then you'll have to adjust
> this accordingly. You can reimplement mlt using the other_mlt hook, just
> copy all what's neccesary from mlt_info into your run_star_extras and
> adjust the line above. Note that you also have to set properly the partial
> derivatives for the scale height, which are required by the newton solver,
> this is currently done in mlt_info in this way
>
> d_scale_height_dvb = scale_height*(dP_dvb/P - d_grav_dvb/grav -
> dRho_dvb/Rho)
>
> Here the variables denoted as *_dvb are arrays containing the partial
> derivatives with respect to each variable. You should be able to figure out
> how itworks by digging a bit in mlt_info. From your modifications, you'll
> need to figure out how to get the partial derivatives for dphi with respext
> to the structure variables.
>
> Cheers
>
> On Tue, May 14, 2019, 07:06 sheyda najafi via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
>
>> Dear MESA users
>>
>> I have changed extra_dpdm to add a new acceleration term to HSE
>> equation in MESA code.
>> (p(i-1)- p(i))/dm_bar(i)=( -standard_cgrav*m(r))/(4*pi* s% r(i)**4) -
>> beta*(clight**2) *rho_face(i) (dphi/dm_bar)
>> therefore
>> extra_dpdm(i)= - beta*(clight**2) *rho_face(i) dphi/dm_bar
>>
>> which i have asked about the quantities and the shape of this new term
>> in previous emails.
>>
>> My question is how does this extra acceleration change the pressure
>> scale height in the code. I can not find the relation. I know that
>> pressure scale height depends on p_face and rho_face and grav. The
>> extra_dpdm has impact on density and pressure but I can not find the
>> relation between grav and extra_dpdm in the code.
>>
>> Thank you very much
>> Sheyda Najafi
>>
>> On 5/7/19, sheyda najafi <sh.najafi8590 at gmail.com> wrote:
>> > 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
>> >>
>> >
>> _______________________________________________
>> mesa-users at lists.mesastar.org
>> https://lists.mesastar.org/mailman/listinfo/mesa-users
>>
>>
>
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