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<p style="margin: 0px 0px 20px; line-height: 30px;"><span style="line-height: normal; font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><b>"Physics, Modeling, and Large Scale Simulations of Turbulent Reactive Flows"</b></span></p>
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<div style=""><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Tomasz Plewa</span><br>
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<div><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Dept. of Scientific Computing,</span></div>
<span style="font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Florida State University</span>
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<div style=""><i><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">NOTE: Please feel free to forward/share this invitation with other groups/disciplines that might be interested in this talk/topic. All are welcome
to attend.</span><br>
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<div style=""><b><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Meeting # 942 7359 5552</span><br>
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<div style=""><span style="color: rgb(0, 0, 0); font-family: Tahoma, Geneva, sans-serif; font-size: 12pt;">Schedule: </span><br>
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<div style=""><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Teatime - Virtual (via Zoom)
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<div style=""><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">* 3:00 to 3:30 PM Eastern Time (US and Canada)</span><br>
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<div style=""><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Colloquium - F2F (in 499 DSL) | Virtual (via Zoom)
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<div style=""><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">* 3:30 to 4:30 PM Eastern Time (US and Canada)</span><br>
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<div style=""><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Abstract:</span><br>
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<span style="text-align: start; display: inline !important; font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">We present the results of simulations of magnetized, reactive turbulence for conditions expected to exist in outer layers
of massive white dwarfs during the advanced stages of the deflagration-driven explosion. In the present scenario an initially quiescent, low density plasma is perturbed by the approaching flame front, which drives turbulence on large scales due to Rayleigh-Taylor
(RT) instability, and self-heated by nuclear burning.</span><br>
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<span style="text-align: start; display: inline !important; font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">We probe a parameter space of this problem by obtaining a series of models systematically varying characteristics of
turbulence and initial strength of the magnetic field. The observed behavior is qualitatively similar to previously reported results of hydrodynamic simulations. Deflagration-to-detonation transition (DDT) is facilitated by the Zel'dovich reactivity gradient
mechanism and occurs about 100 ms after the self-heating of plasma is enabled. Such relatively short detonation delay times are observed despite the fact that the turbulence is driven using relatively lower, realistic energies characteristic of the RT-driven
supernova flame turbulence. The resulting turbulence Mach number is ~0.3.</span><br style="text-align: start;">
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<span style="text-align: start; display: inline !important; font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">We find the DDT delay time is a sensitive function of the turbulence compressibility with shorter delay times observed
in models in which most of the driving energy injected on large scales is in solenoidal modes. Such perturbations are consistent with the RT-driven turbulence. For realistic initial magnetic field values(~10 MG or higher), the field is rapidly amplified with
the average plasma beta reaching about 0.1 well before carbon ignites.</span><br style="text-align: start;">
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<span style="text-align: start; display: inline !important; font-family: Tahoma, Geneva, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">We discuss the magnetic field amplification mechanism, how the magnetic field participates in the process of preconditioning,
and its role in accelerating DDT in the context of the Zel'dovich mechanism. Our results motivate observations aimed at measuring magnetic fields in Type Ia supernovae and future theoretical and computational studies of magnetized white dwarfs.</span>
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