Diffusion in stellar interiors: critical tests of three numerical methods
نویسندگان
چکیده
We describe and discuss the properties of three numerical methods for solving the diffusion equation for the transport of the chemical species and of the angular momentum in stellar interiors. We study through numerical experiments both their accuracy and their ability to provide physical solutions. On the basis of new tests and analyses applied to the stellar astrophysical context, we show that the most robust method to follow the secular evolution is the implicit finite differences method. The importance of correctly estimating the diffusion coefficient between mesh points is emphasized and a procedure for estimating the average diffusion coefficient between a convective and a radiative zone is described.
منابع مشابه
v 1 6 A pr 1 99 3 Element Diffusion in the Solar Interior
We study the diffusion of helium and other heavy elements in the solar interior by solving exactly the set of flow equations developed by Burgers for a multi-component fluid, including the residual heat-flow terms. No approximation is made concerning the relative concentrations and no restriction is placed on the number of elements considered. We give improved diffusion velocities for hydrogen,...
متن کاملdynamos: challenges for next generation models
Three-dimensional (3D) global dynamo models numerically simulate convection and magnetic field generation in the fluid interiors of planets and stars. Geodynamo models, for example, currently produce largescale magnetic fields that, outside the core, resemble the Earth’s surface field to first order. However, no 3D global model has yet been able to afford the spatial resolution required to simu...
متن کاملOn the Propagation of Non Stationary Pressure Waves in Stellar Interiors
An analysis of the propagation of non stationary waves in the adiabatic region of stellar interior is presented. An equation of motion with an effective potential is derived, similar to the Zerilli equation known in the propagation of gravitational waves. The Huyghens principle is violated in this case and the energy diffusion outward null cones is expected. Numerical calculations demonstrate t...
متن کاملA numerical investigation of a reaction-diffusion equation arises from an ecological phenomenon
This paper deals with the numerical solution of a class of reaction diffusion equations arises from ecological phenomena. When two species are introduced into unoccupied habitat, they can spread across the environment as two travelling waves with the wave of the faster reproducer moving ahead of the slower.The mathematical modelling of invasions of species in more complex settings that include ...
متن کاملDevelopment of an Implicit Numerical Model for Calculation of Sub and Super Critical Flows
A two dimensional numerical model of shallow water equations was developed tocalculate sub and super-critical open channel flows. Utilizing an implicit scheme the steady stateequations were discretized based on control volume method. Collocated grid arrangement was appliedwith a SIMPLEC like algorithm for depth-velocity coupling. Power law scheme was used fordiscretization of convection and dif...
متن کامل