Latest news:

Effect of Radiation on Wave Propagation

We simulate and study wave propagation in stratified atmospheres and what effect radiative transfer has on them. Our model is a combination of the MHD equations and the M1 model of radiative transfer.

As can be seen in the animation to the left, radiation keeps the temperature roughly constant. Furthermore, accounting for radiation results in dampened and slowed down hydrodynamic/MHD waves.

Similar effects can be observed in several spatial dimensions and with complicated magnetic fields.

Read more Mar 4, 2010

Realistic test:

Simulation with Observed Data from the Sun

We simulate and study wave propagation in stellar atmospheres, in particular the atmosphere of the Sun.

The animation to the left shows the result of a simulation where we have used data oberved by SOHO. In particular the magnetic field is realistic and the boundary condtions at the bottom (driving the waves) are as observed in the atmosphere of the Sun at a particular location and time.

These results show the robustness of our proposed scheme.

Read more Nov 12, 2009

Recent project:

Wave propagation in the solar atmosphere

We simulate and study wave propagation in stellar atmospheres, in particular the atmosphere of the Sun.

One of the problems to solve is the so called coronal heating problem . It relates to the question of why the temperature of the Sun's corona is millions of kelvins higher than that of the surface.

Wave propagation is modeled by the equations of ideal MHD equations, together with the gravity source term. The waves are modeled as perturbations of non-isothermal steady states of the system.

The equations are discretized by novel finite volume schemes, described in a forthcoming paper. These schemes are observed to be robust and resolve the complex physics well.

Read more Jul, 2009

Older results:

Magento-hydrodynamic equations

Magnetohydrodynamics (MHD) describe the dynamics of electrically conducting fluids, also known as plasmas. The picture on the left hand side shows the interaction of a strong shock front with a dense plasma cloud, generating a bow shock in the front, tail shocks in the rear and an interesting turbulent-like structure. It was computed by a FV scheme based on the Godunov-Powell form of the ideal MHD equations. This form is entropy symmetrizable as well as Galilean invariant.

We derive suitable approximate Riemann solvers and discretize the Godunov-Powell source term in an upwinded manner. In addition, we design high order positivity preserving ENO and WENO reconstructions. Numerical experiments illustrate the accuracy and stability of the resulting schemes, particularly on fine meshes, see the Publications section.

2007-2008