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arXiv · 2109.03482

Time-Evolving to Space-Evolving Thermal Instability of a Porous Medium Flow

Antonio Barletta
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Abstract

The Rayleigh-B\'enard instability of the stationary throughflow in a horizontal porous layer, also known as Prats' problem, is here analysed in a fresh new perspective. In fact, the classical analysis of the linear instability, carried out by employing space-periodic Fourier modes, is here reconsidered by focussing on the effects of time-periodic and space-evolving modes. The basic stationary flow is assumed to be perturbed by a localised source of perturbation which is steady-periodic in time. Then, the streamwise development of such perturbations is monitored in order to detect their possible amplification or decay in the direction of propagation. Accordingly, the spatial stability/instability threshold is determined. The study is carried out by employing a Fourier transform formalism, where the transformed variable is time.

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Antonio Barletta. 2021-09-08. Time-Evolving to Space-Evolving Thermal Instability of a Porous Medium Flow. https://doi.org/10.1063/5.0076368

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