A Lorentz Force Powered Controllable Micro-Jet Injection System

International Journal of Heat and Fluid Flow

Angelino

et al. 2019

Section: Introductionmentioning

confidence: 99%

Large eddy simulation and self-similarity analysis of the momentum spreading in the near field region of turbulent submerged round jets

International Journal of Heat and Fluid Flow

Angelino

et al. 2019

“…The parameters determining the dispersion of particles, or droplets, in jets, [40][41][42], and the heat transfer from a jet to a solid surface, [43][44], are the Reynolds number (Re) and the turbulence intensity (Ti). In applications like micro-jets for drug injection, [45][46], and recent welding technologies, [47][48], low turbulence intensities and moderate Reynolds numbers are requested, evidencing the role of molecular diffusion. The diffusivity of a particle is proportional to its radius, according to the Stoke-Einstein relation, [49], and the Cunningham empirical equation, [50], giving a Schmidt number of air in the range from 1 to 100 for particle radius of the order of .…”

Section: Introductionmentioning

confidence: 99%

Passive scalar diffusion in three-dimensional turbulent rectangular free jets with numerical evaluation of turbulent Prandtl/Schmidt number

International Communications in Heat and Mass Transfer

Angelino

et al. 2018

The passive scalar spreading of fluids with laminar Prandtl or Schmidt number, , Pr Sc , equal to 1 in turbulent rectangular submerged free jets is analyzed by means of numerical simulation and theoretical analysis in the Reynolds number range 5000-40,000. The numerical investigation is carried out by means of a three-dimensional (3D) Large Eddy Simulation (LES) approach with the dynamic Smagorinsky model. A new mathematical model allows to obtain a simplified description of the passive scalar spreading in the largest area of the flow field, the Fully Developed Region (FDR). The present three-dimensional (3D) investigation shows that the passive scalar spreading follows a self-similarity law in the Fully Developed Region (FDR), as well as in the mean Undisturbed Region of Flow (URF) and in the Potential Core Region (PCR), similarly to what found in the Near Field Region (NFR) of rectangular submerged free jets, investigated with a two-dimensional (2D) approach. The turbulent Prandtl or Schmidt number is evaluated numerically and is found to be inversely proportional to the mean velocity gradient in the PCR. The present 3D numerical results show that the turbulent Prandtl or Schmidt number is zero in most part of the mean URF, and PCR, while it assumes different values outside. In the FDR the turbulent Prandtl or Schmidt number is constant and approximately equal to 0.7, in agreement with the literature, showing that turbulence affects momentum and passive scalar in a different way.

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“…In several applications of circular jets it is desirable to have high Reynolds number (Re>40,000) and turbulence intensities (Ti>5%) and the dispersed phase can be described by some simplified solutions, as in the Fully Developed Region (FDR) [6][7]. In other applications, such as micro-jets for drug injection [8][9], and recent welding technologies [10][11], low turbulence intensities (Ti<5%) and moderate Reynolds numbers (2,000<Re<20,000) are requested. The dispersed phase field appears to be complex, and there is no mathematical model describing it.…”

Section: Introductionmentioning

confidence: 99%

Passive scalar diffusion in the near field region of turbulent rectangular submerged free jets

International Journal of Heat and Mass Transfer

Gori

2017