Universal Structure of Turbulent Radiative Mixing Layers
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arXiv
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| Main Authors: | , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866917082847772672 |
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| author | Sharma, Prateek Kumar, Arnav Datta, Dipayan Babul, Arif Das, Rishita Aditya, Konduri |
| author_facet | Sharma, Prateek Kumar, Arnav Datta, Dipayan Babul, Arif Das, Rishita Aditya, Konduri |
| contents | Turbulent radiative mixing layers (TRMLs), where shear-driven turbulence between dense and diffuse gas produces rapidly cooling intermediate-temperature gas, are ubiquitous in the interstellar and circumgalactic media. Using a quasi-steady Reynolds decomposition, we separate mean and turbulent components. In quasi-isobaric TRMLs, upstream gas cools and compresses before streamwise momentum is fully mixed, yielding a negative shear stress (R_{xz}) and a positive compressive stress (R_{zz}) that together sustain a steady radiative conversion of hot to cold gas. A pronounced thermal-pressure dip develops within the TRML, while radiative losses are offset by the divergences of enthalpy flux and (subdominant) turbulent heat flux (Q_t). The volume-averaged temperature follows a tanh profile, resulting in universal emissivity distributions that are consistent with simulations. Contrary to previous claims, the cooling-rate surface density saturates and becomes independent of box size in the strong-cooling limit, establishing the universal structure of TRMLs. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_03802 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Universal Structure of Turbulent Radiative Mixing Layers Sharma, Prateek Kumar, Arnav Datta, Dipayan Babul, Arif Das, Rishita Aditya, Konduri Astrophysics of Galaxies Fluid Dynamics Turbulent radiative mixing layers (TRMLs), where shear-driven turbulence between dense and diffuse gas produces rapidly cooling intermediate-temperature gas, are ubiquitous in the interstellar and circumgalactic media. Using a quasi-steady Reynolds decomposition, we separate mean and turbulent components. In quasi-isobaric TRMLs, upstream gas cools and compresses before streamwise momentum is fully mixed, yielding a negative shear stress (R_{xz}) and a positive compressive stress (R_{zz}) that together sustain a steady radiative conversion of hot to cold gas. A pronounced thermal-pressure dip develops within the TRML, while radiative losses are offset by the divergences of enthalpy flux and (subdominant) turbulent heat flux (Q_t). The volume-averaged temperature follows a tanh profile, resulting in universal emissivity distributions that are consistent with simulations. Contrary to previous claims, the cooling-rate surface density saturates and becomes independent of box size in the strong-cooling limit, establishing the universal structure of TRMLs. |
| title | Universal Structure of Turbulent Radiative Mixing Layers |
| topic | Astrophysics of Galaxies Fluid Dynamics |
| url | https://arxiv.org/abs/2509.03802 |