Rajhans, AbhishekTripathi, DurgeshBradshaw, Stephen J.Kashyap, Vinay L.Klimchuk, James A.2022-03-242022-03-242022Rajhans, Abhishek, Tripathi, Durgesh, Bradshaw, Stephen J., et al.. "Flows in Enthalpy-based Thermal Evolution of Loops." <i>The Astrophysical Journal,</i> 924, (2022) IOP Publishing: https://doi.org/10.3847/1538-4357/ac3009.https://hdl.handle.net/1911/112033Plasma-filled loop structures are common in the solar corona. Because detailed modeling of the dynamical evolution of these structures is computationally costly, an efficient method for computing approximate but quick physics-based solutions is to rely on space-integrated 0D simulations. The enthalpy-based thermal evolution of loops (EB℡) framework is a commonly used method to study the exchange of mass and energy between the corona and transition region. EB℡ solves for density, temperature, and pressure, averaged over the coronal part of the loop, velocity at coronal base, and the instantaneous differential emission measure distribution in the transition region. The current single-fluid version of the code, EB℡2, assumes that at all stages the flows are subsonic. However, sometimes the solutions show the presence of supersonic flows during the impulsive phase of heat input. It is thus necessary to account for this effect. Here, we upgrade EB℡2 to EB℡3 by including the kinetic energy term in the Navier–Stokes equation. We compare the solutions from EB℡3 with those obtained using EB℡2, as well as the state-of-the-art field-aligned hydrodynamics code HYDRAD. We find that the match in pressure between EB℡3 and HYDRAD is better than that between EB℡2 and HYDRAD. Additionally, the velocities predicted by EB℡3 are in close agreement with those obtained with HYDRAD when the flows are subsonic. However, EB℡3 solutions deviate substantially from HYDRAD’s when the latter predicts supersonic flows. Using the mismatches in the solution, we propose a criterion to determine the conditions under which EB℡ can be used to study flows in the system.engOriginal content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Journal articleRajhans_2022_ApJ_924_13https://doi.org/10.3847/1538-4357/ac3009