Shapes and speeds of forced premixed flames
| Autor: | Joulin, Guy, Denet, Bruno |
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| Rok vydání: | 2014 |
| Předmět: | |
| Zdroj: | Physical Review E 89(6) 063001 (2014) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevE.89.063001 |
| Popis: | Steady premixed flames subjected to space-periodic steady forcing are studied via inhomogeneous Michelson-Sivashinsky (MS) and then Burgers equations. For both, the flame slope is posited to comprise contributions from complex poles to locate, and from a base-slope profile chosen in three classes (pairs of cotangents, single-sine functions or sums thereof). Base-slope-dependent equations for the pole locations, along with formal expressions for the wrinkling-induced flame-speed increment and the forcing function, are obtained on excluding movable singularities from the latter. Besides exact few-pole cases, integral equations that rule the pole-density for large wrinkles are solved analytically. Closed-form flame-slope and forcing-function profiles ensue, along with flame-speed increment vs forcing-intensity curves; numerical checks are provided. The Darrieus-Landau instability mechanism allows MS flame speeds to initially grow with forcing intensity much faster than those of identically forced Burgers fronts; only the fractional difference in speed increments slowly decays at intense forcing, which numerical (spectral) timewise integrations also confirm. Generalizations and open problems are evoked. Comment: Revised version submitted to Phys. Rev.E |
| Databáze: | arXiv |
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