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DIRECT NUMERICAL SIMULATION OF NON-ISOTHERMAL TURBULENT WALL-JETS

Daniel Ahlman
Linne Flow Centre, Dept. of Mechanics, Royal Institute of Technology SE-100 44 Stockholm, Sweden

Geert Brethouwer
Linne FLOW Centre, KTH Mechanics Royal Institute of Technology 100 44 Stockholm, Sweden

Arne V. Johansson
Linne FLOW Centre, Dept. of Mechanics, Royal Institute of Technology SE-100 44 Stockholm, Sweden

Аннотация

Direct numerical simulations of plane turbulent non-isothermal wall-jets are performed and compared to the isothermal case. Two non-isothermal cases are studied; a cold jet propagating in a warm environment with inlet ambient to jet density ratio of ρ/ρj = 0.4, and a warm jet in a cold surrounding where ρaj = 1.7 at the inlet. The ambient and wall temperature are kept equal and constant, and a temperature dependent viscosity is used. Results from the non-isothermal cases are compared to those obtained in a previously studied isothermal wall-jet with the same inlet Reynolds and Mach numbers. A passive scalar is also included in the simulations to study mixing. The influence of the varying temperature on the development and jet growth is studied as well as the influence on turbulence statistics and fluctuation intensities of the temperature and passive scalar. The warm jet contains smaller turbulent structures, and the cold jet larger, than the isothermal one. The change in structure and intensity affect the development and mixing in the jets.