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Heating by transverse waves in simulated coronal loops

机译:模拟冠状圈中横波加热

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Context. Recent numerical studies of oscillating flux tubes have established the significance of resonant absorption in the damping of propagating transverse oscillations in coronal loops. The nonlinear nature of the mechanism has been examined alongside the Kelvin-Helmholtz instability, which is expected to manifest in the resonant layers at the edges of the flux tubes. While these two processes have been hypothesized to heat coronal loops through the dissipation of wave energy into smaller scales, the occurring mixing with the hotter surroundings can potentially hide this effect. Aims. We aim to study the effects of wave heating from driven and standing kink waves in a coronal loop. Methods. Using the MPI-AMRVAC code, we perform ideal, three dimensional magnetohydrodynamic (MHD) simulations of both (a) footpoint driven and (b) free standing oscillations in a straight coronal flux tube, in the presence of numerical resistivity. Results. We have observed the development of Kelvin-Helmholtz eddies at the loop boundary layer of all three models considered here, as well as an increase of the volume averaged temperature inside the loop. The main heating mechanism in our setups was Ohmic dissipation, as indicated by the higher values for the temperatures and current densities located near the footpoints. The introduction of a temperature gradient between the inner tube and the surrounding plasma, suggests that the mixing of the two regions, in the case of hotter environment, greatly increases the temperature of the tube at the site of the strongest turbulence, beyond the contribution of the aforementioned wave heating mechanism.
机译:上下文。振荡通量管的最新数值研究已经确定了共振吸收在冠状环中传播的横向振荡的阻尼中的重要性。与开尔文-亥姆霍兹不稳定性一起研究了该机理的非线性性质,该不稳定性预计会出现在通量管边缘的共振层中。假设这两个过程是通过将波能的耗散散布到较小的尺度来加热日冕环,但与较热的环境发生混合可能会隐藏这种效应。目的我们的目的是研究日冕环中驱动的和站立的扭结波引起的波加热效应。方法。使用MPI-AMRVAC代码,在存在数字电阻率的情况下,我们对(a)脚位驱动和(b)日冕磁通量管中的自立振动进行了理想的三维磁流体动力学(MHD)模拟。结果。我们已经观察到这里考虑的所有三个模型的回路边界层处的Kelvin-Helmholtz涡流的发展,以及回路内部体积平均温度的增加。在我们的设置中,主要的加热机制是欧姆耗散,如脚附近温度和电流密度的较高值所示。在内管和周围等离子体之间引入温度梯度表明,在较热的环境中,两个区域的混合会大大增加最强湍流部位的管温度,超过了前述的波加热机构。

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