Abstract
We conduct non-isothermal large eddy simulations (LESs) of flow past a heated cylinder (Re = 3900) to investigate flow physics throughout the wake region and develop a foundation upon which future heat flux wall models can be built (both for wall-modeled LES and other lower fidelity models) for mathematical closure of the energy equation. A rigorous validation of the mesh is made under isothermal conditions with results showing a closer match to experimental data than any other LES studies to date. The insights gained into the mesh design and approach are discussed. Simulation of non-isothermal flow is performed on the validated mesh for temperature differences between the cylinder surface and the freestream of 25 K and 300 K. The mesh design and realistic (temperature-dependent) thermodynamic property variations play key roles in predicting delayed separation, larger re-circulation zones, and enhanced turbulence intensity for the higher temperature difference case. The effect of both temperature differences on the flow is analyzed, and a new scaling of the flow domain is proposed to gain further insight into non-isothermal flow physics. Key scaling variables, friction temperature and friction velocity, are able to reduce nearly all of the temperature dependence of first and second order flow statistics, including turbulent heat fluxes. This leads to the finding that the turbulent heat flux in the wake region scales with the wall heat flux irrespective of the temperature difference in the flow.
| Original language | English |
|---|---|
| Article number | 0031831 |
| Journal | Physics of Fluids |
| Volume | 32 |
| Issue number | 12 |
| DOIs | |
| State | Published - Dec 1 2020 |
| Externally published | Yes |
Funding
We gratefully acknowledge financial support through the Small Business Technology Transfer (STTR) Phase I program from the U.S. Navy under the project titled “A Framework for Modeling Turbulent Flow with Conjugated Heat Transfer,” Contract No. N6833519C0775, awarded to Advanced Cooling Technologies and Texas A&M University. This research was driven by the need to address the gap in the available data observed during the Phase I STTR program. Interactions with Dr. John Willard and Dr. Allan Aubert, the technical points of contact at the Naval Air Warfare Center—Aircraft Division, Propulsion and Power, helped to enhance the long-term relevance of our efforts. We also recognize the contributions of Texas A&M University’s High-Performance Research Computing (HPRC) who supplied the requisite resources for this computational investigation. The early stages of this project also partially benefited from the high-performance computing infrastructure of the Extreme Science and Engineering Discovery Environment (XSEDE), Allocation Grant No. DMR180017. The XSEDE is supported by the National Science Foundation (NSF), Grant No. ACI-1053575. NAVAIR Public Release 2020-623. Distribution Statement A - Approved for public release; distribution is unlimited.