photospheric mhd simulation of solar pores robert cameron alexander vögler vasily zakharov manfred...
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Photospheric MHD simulation of solar pores
Robert CameronAlexander VöglerVasily Zakharov
Manfred Schüssler
Max-Planck-Institut für Sonnensystemforschung Katlenburg-Lindau, Germany
MSI Workshop
Equations
• Compressible non-ideal MHD with radiation
– Momentum equation, Lorentz force and artificial viscosity
– Continuity equation– Induction equation, with proper diffusion– Energy equation, with non-gray radiation– Equation of state, including partial ionization
Setup
• Box size 288 x 288 x 100 grid points
• Boundary conditions Vertical field above box OR Potential field above box
• Initial Conditions Two total fluxes considered (today only larger case considered). Simulate 2-D to get near equilibrium then create 3-D initial condition. Injection of some opposite polarity flux in some runs
12 Mm 12 Mm1.4
Mm
The MURaM code
• Finite Differences• Fixed, uniformly spaced mesh (288 x 288 x 100)• Forth order in space• Runge-Kutta• Hyper Diffusivities
• Short Characteristic method for radiation
University of Chicago: Basic MHD codeMPS (Alexander Vögler): Radiative Transfer
Hyper Diffusivities
Results
Intensity|B| (tau=1)
Bvert (tau=1) Uvert (tau=1)
Vertical StructureP
ore
sim
ulat
ion
Qui
et S
un S
imul
atio
nO
bser
ved
pore
s (S
utte
rlin)
Sim
ulat
ions
Vertical Structure 2: Energy transport
Temperature Vertical Field
Z=-240
Z=-360
Z=-480
Vertical Structure 2: Energy transport
Temperature at a fixed geometrical height (3 copies)
Vertical Structure 2: Energy transport
Intensitylog(Tau constant geometrical depth)
Vertical magnetic field (Tau=1 surface)
Intensity Tau=1,Tau=0.1
Reference frame
Slice
Magnetic field linesMagnetic energyTau=1 level
Temperature contoursTemperatureTau=1 level
Radial Structure
TAU=1
TAU=0.1
Radial Structure
TAU=1
TAU=0.1
Topology
From bottom to topFrom top to bottomInverse U loops
Evolution
Flux decay from pore Average field strength(depends on how pore is defined)
Evolution
Intensity v size
A view from the side
500nm
=0.7 0.5 0.2
Main conclusions
• Thermal properties of pore similar to observations• Magnetic fields and magnetic field gradient sensitive to
definition of the pores edge. • Energy transport involves plumes which are dark at
surface (?)• Topology is becoming interesting (but the pore is still
small).• Side views have reasonable enhancements, but is quite
smooth.