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Project > Computational Astrophysics

Computational Astrophysics (formerly CFD-MHD)

Computational Astrophysics (CompAS) Website
Our simulations indicate that in the study of the runaway (type III) migration, it is important to carry out a fully self consistent treatment of the gravitational interaction between the disk and the embedded planet.
On the Orbital Evolution of a Jovian Planet Embedded in a Self-Gravitating Disk
The numerical solutions of a D2 disk for N=1024, the profiles are surface density (left-top), the x-directional force (right-top), the y-directional force(left-bottom), and radial force(right-bottom).
Self-gravitational force calculation of infinitely thin gaseous disks
The numerical solutions of a D2 disk for N=1024, the profiles are surface density (left-top), the x-directional force (right-top), the y-directional force(left-bottom), and radial force(right-bottom).
Self-gravitational force calculation of infinitely thin gaseous disks
The left panel corresponds to the particle image showing the face on and two edge on views of an initially axisymmetric disk. The right panel shows the formation of a bar which produces a peanut shaped morphology.
The Effect of Bars and Transient Spirals on the Vertical Heating in Disk Galaxies
The left panel corresponds to the particle image showing the face on and two edge on views of an initially axisymmetric disk. The right panel shows the formation of a bar which produces a peanut shaped morphology.
The Effect of Bars and Transient Spirals on the Vertical Heating in Disk Galaxies
Numerical calculations reveal that the striking features in NGC 6782 can be reproduced provided that the gas flow is governed by the gravitational potential associated with a slowly rotating strong bar.
Hydrodynamical Simulations of the Barred Spiral Galaxy NGC 6782
Three dimensional hydrodynamical simulations show that the substellar mass objects produce detectable signatures, corresponding to density contrasts of 10--200 % and arm separations of 10--400 AU at 100 AU distance, for the wake induced by a Jupiter to brown dwarf mass object orbiting a solar mass AGB star.
Probing Substellar Companions of Asymptotic Giant Branch Stars through Spirals and Arcs
Three dimensional hydrodynamical simulations show that the substellar mass objects produce detectable signatures, corresponding to density contrasts of 10--200 % and arm separations of 10--400 AU at 100 AU distance, for the wake induced by a Jupiter to brown dwarf mass object orbiting a solar mass AGB star.
Probing Substellar Companions of Asymptotic Giant Branch Stars through Spirals and Arcs
The above figures show the density enhancement of the spiral-onion shell shape (a) in the equatorial plane, (b) in a meridional plane, and (c) as a function of the distance from the system center along +x (red), -y (yellow), -x (green), +y (blue), and z (cyan) axes.
Gravitationally Induced Density Wake of a Circularly Orbiting Object As an Interpretative Framework of Ubiquitous Spirals and Arcs
Observations of SNIa rates as a function of redshift suggest the existence of a short delay time population of 100 Myr and a long delay time population of 3-4 Gyr.
Impact of Type Ia Supernova Ejecta on a Helium Star Binary Companion
Observations of SNIa rates as a function of redshift suggest the existence of a short delay time population of 100 Myr and a long delay time population of 3-4 Gyr.
Impact of Type Ia Supernova Ejecta on a Helium Star Binary Companion
Simulations of our CFW models from 1 to 6, at the age of ~160 yr. Parts (a), (c), (e), (g), (i), and (k) show the number density of hydrogen nuclei in logarithmic scale. Parts (b), (d), (f), (h), (j), and (l) show the temperature in logarithmic scale. The molecular fractions f = 0.1 (white line) and f = 0.49 (magenta line) are shown to outline the distribution of molecular gas. The separation between the AGB wind and the CFW is shown by the color tracer c = 0.5 (gray line, at which half is AGB wind and half is CFW). The CFW is atomic at 10,000 K in models 1 and 2, while is molecular at 1000 K in models 3–6. The CFW is steady in models 1 and 3, while is pulsed with A = 0.5 in models 2 and 4, A = 0.3 in model 5, and A = 0.1 in model 6. Parts (A)−(F) show respectively the blow-ups for the regions in the boxes (A)−(F).
Collimated fast winds in Preplanetary Nebulae
In numerical simulations of the star-disk system, after the relaxation, the disk is truncated at the truncation radius R_t. Position of the R_t is close to the line of balance of the disk ram pressure and the magnetic pressure, which is located between a central object and the disk inner radius.
Magnetospheric Accretion and Ejection of Matter in Resistive MHD Simulations
In numerical simulations of the star-disk system, after the relaxation, the disk is truncated at the truncation radius R_t. Position of the R_t is close to the line of balance of the disk ram pressure and the magnetic pressure, which is located between a central object and the disk inner radius.
Magnetospheric Accretion and Ejection of Matter in Resistive MHD Simulations
In numerical simulations of the star-disk system, after the relaxation, the disk is truncated at the truncation radius R_t. Position of the R_t is close to the line of balance of the disk ram pressure and the magnetic pressure, which is located between a central object and the disk inner radius.
Magnetospheric Accretion and Ejection of Matter in Resistive MHD Simulations
Simulations of winds of terminal speed of 300 km/s (~3Va) and ambient densities 10E-20 g/cm^3. The results are plotted on four-panels to illustrate selected time frames of 100, 400, 700, and 1000 years of evolution time. The appearance of the resultant de
Simulations of winds

CFD-MHD (changed into CompAS, in Feb. 2012, for Computational Astrophysics) initiative has been a joint research project of the Institute of Astronomy and Astrophysics (ASIAA) and the Institute of Mathematics (ASIM) of the Academia Sinica, and the Department of Mathematics of the National Taiwan University. Its main goal is to develop high-performance codes of computational fluid dynamics and magnetohydrodynamics (CFD-MHD) for astrophysical problems.

We have successfully developed a set of 2-D/3-D Godunov codes based on exact/approximate Reimann solver. They are featured with self-gravitation and characteristics decomposition on the boundary, guaranteed non-reflection. At present we are applying these codes to the study of two main problems: the structure and evolution of gas disks in spiral galaxies and the planet migration in protostellar disks.

link to project site

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