Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session Y15: Stellar & General Fluid Dynamics |
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Sponsoring Units: DFD Chair: Xifan Wu, Temple University Room: 304 |
Friday, March 7, 2014 8:00AM - 8:12AM |
Y15.00001: Toward Connecting Core-Collapse Supernova Explosions with Observations of their Supernova Remnants Timothy Handy, Tomasz Plewa, Artur Gawryszczak We study the process of collapse of a massive star and the following explosion process until the formation of a young supernova remnant in a single simulation. These new models are critically evaluated against a database of core-collapse supernovae (ccSNe) explosion models obtained with a standard supernova code. We develop a multiphysics hydrocode capable of accounting for physics from before collapse occurs until the supernova remnant phase. This enables ccSNe studies with a single code without the need of remapping or transferring data between multiple codes. The code uses a new algorithm to account for the effects of neutrino-matter interaction in the collapsing stellar core. The algorithm uses ray-casting in three dimensions and enables performing collapse and explosion simulations on AMR meshes, including non-radial discretizations. Heating due to radioactive decay, and magnetization of the ejecta are included in the model. The asymmetry of the explosion continues to play a role well beyond the shock breakout phase. In particular, the lateral momentum deposited in the process of shock revival helps shape the supernova ejecta. Another important contributing factor shaping the ejecta is due to radioactive decay of nucleosynthetic products of the explosion. [Preview Abstract] |
Friday, March 7, 2014 8:12AM - 8:24AM |
Y15.00002: The Sun is Condensed Matter and has a Real Surface Pierre-Marie Robitaille The idea that the Sun was a gaseous in nature was born from 1858-65. At that time, a group of men, including Herbert Spencer, Father Angelo Secchi, Warren de la Rue, Balfour Stewart, and Benjamin Loewy, advanced that the Sun was a ball of gas. In 1865, Herv\'{e} Faye was the first to argue that the solar surface was merely an illusion. Dismissing all signs to the contrary, solar physics has promoted this idea to the present day, as manifested by the Standard Solar Model. In this work, overwhelming observational evidence will be presented that the Sun does indeed possess a distinct surface (see P.M. Robitaille, Forty Lines of Evidence for Condensed Matter --- \underline {The Sun on Trial}: Liquid Metallic Hydrogen as a Solar Building Block, Progress in Physics, 2013, v. 4, 90-143). Our telescopes and satellites are sampling real structures on the surface of the Sun. [Preview Abstract] |
Friday, March 7, 2014 8:24AM - 8:36AM |
Y15.00003: Branching of Tsunami Waves Henri-Philippe Degueldre, Jakob Metzger, Ragnar Fleischmann, Theo Geisel Branched flow is a universal phenomenon occuring in particle or wave flows propagating through weakly scattering, correlated, random media. Even for very weak disorder in the medium, it can lead to extremely strong fluctuations in the wave intensity. We show how tsunami waves are affected by branching. We model the tsunamis propagating over the ocean floor with its complex height fluctuations by the linearized shallow water wave equations with random bathymetries. We calculate the typical distance from the source at which the strongest wave fluctuations occur as a function of the statistical properties of the bathymetry. [Preview Abstract] |
Friday, March 7, 2014 8:36AM - 8:48AM |
Y15.00004: Imaging heat transfer processes in a fluid with temperature sensitive paint Jun Huang, Tianshu Liu, Weili Luo The temperature profile inside a fluid was imaged by temperature sensitive paint in a quasi one-dimensional cell, where temperature gradients were established by heating on one side of the sample and cooling on the other. Similar experiment was performed on colloids consisting nanoparticles suspended in solvent. The change of the profile for different heat-transfer processes as functions of time will be discussed. [Preview Abstract] |
Friday, March 7, 2014 8:48AM - 9:00AM |
Y15.00005: ABSTRACT WITHDRAWN |
Friday, March 7, 2014 9:00AM - 9:12AM |
Y15.00006: Adjoint problem in duct acoustics and its reciprocity to forward problem by the Time Domain Wave Packet method Ibrahim Kocaogul, Fang Hu, Xiaodong Li Radiation of acoustic waves at all frequencies can be obtained by Time Domain Wave Packet (TDWP) method in a single time domain computation. Other benefit of the TDWP method is that it makes possible the separation of acoustic and instability wave in the shear flow. The TDWP method is also particularly useful for computations in the ducted or waveguide environments where incident wave modes can be imposed cleanly without a potentially long transient period. The adjoint equations for the linearized Euler equations are formulated for the Cartesian coordinates. Analytical solution for adjoint equations is derived by using Green's function in 2D and 3D. The derivation of reciprocal relations is presented for closed and open ducts. The adjoint equations are then solved numerically in reversed time by the TDWP method. Reciprocal relation between the duct mode amplitudes and far field point sources in the presence of the exhaust shear flow is computed and confirmed numerically. Applications of the adjoint problem to closed and open ducts are also presented. [Preview Abstract] |
Friday, March 7, 2014 9:12AM - 9:24AM |
Y15.00007: Ab initio theory of X-ray emission spectral of liquid water Charles Swartz, Santra Biswajit, Robert DiStasio, Xifan Wu X-ray emission spectral (XES) has recently been established as a powerful experimental tool in detecting the local H-bond network of liquid water. In the current work, we have developed an {\it ab initio} scheme for calculating the XES spectra of water. Based on the equilibrium trajectories generated by {\it ab initio} molecular dynamics, we perform additional atomic dynamics in the presence of a core-hole within the time scale corresponding to the experimental core-hole lifetime. The XES spectra is then determined by computing the transition matrix based on many body perturbation theory within the GW approximation. It is found that both the core-hole dynamics and the ensemble average of the local chemical environment, due to fluctuations of the H-bond network, are crucial in obtaining a physically meaningful XES spectra of liquid water. [Preview Abstract] |
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