BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:Explicit filtering large eddy simulation for turbulent flows - San tosh Hemchandra (Indian Institue of Science) DTSTART:20221125T124500Z DTEND:20221125T134500Z UID:TALK192719@talks.cam.ac.uk CONTACT:Paras Vadher DESCRIPTION:Large eddy simulation (LES) for turbulent flows aims to provid e physically realistic and time accurate predictions of the dynamics of a range of large length and time scale flow motions. The expectation from th is approach is that of achieving improved prediction accuracy of the stati stics of flow field quantities over traditional Reynolds/Favre averaged me thods while realistically matching available computational resources. Addi tionally\, LES is expected to be a source for training data needed data dr iven flow prediction and analysis methods. For both these reasons\, realiz ing accurate LES for technologically relevant turbulent flows in realistic geometries is an important research problem.\n\nThe explicit filtering LE S (EFLES) method formulated by Joseph Mathew at IISc along with Rainer Fri edrichs and other colleagues at TU Munich\, is one potential approach to a chieving reliable LES. EFLES is formally derived from the approximate deco nvolution modelling (ADM) approach to LES. Formally\, the method involves evolving the flow state using a stable time accurate numerical method and applying a low pass filtering step on the computed fields at every time st ep. The latter ensures that turbulent kinetic energy generated by large sc ale resolved motions does not β€œpile up” at the smallest scale and cont aminate the dynamics of large scales. In addition\, with mesh refinement\, EFLES smoothly reduces to a DNS with no additional modification of the me thod.\n\nThe talk will present a recent extension of this method to reacti ng turbulent flows developed by my research group in IISc and show example s of computations from published and ongoing work. The simulation studies that will be discussed are as follows. First\, a premixed turbulent round methane-air jet flame at an equivalence ratio of 0.8 and unburnt gas tempe rature of 800 K. The nominal 1D premixed flame speed and thermal thickness are\, 𝑠𝐿=2.0 π‘šπ‘ βˆ’1 and 𝛿𝐿=300 πœ‡π‘š respectively. T he nominal turbulent Reynolds number\, 𝑅𝑒𝑑=34 and Karlovitz numbe r\, πΎπ‘Ž=25\, places the flame in the thin reaction zones regime of tu rbulent premixed combustion. LES and DNS results for flow statistics will be compared for this flame. The second case is a model swirl stabilized ga s turbine combustor\, PRECCINSTA at DLR Stuttgart with a nozzle flow 𝑅 𝑒=24\,000. In addition to comparing flows statistics with experimental measurements for this case\, I will also present results comparing charact eristics of coherent self-excited large scale flow dynamics using spectral POD of measured and LES data. These results demonstrate the validity of u sing EFLES for turbulent reacting flows. LOCATION:LR12 END:VEVENT END:VCALENDAR