Models LaGrangian particle tracking

Eulerian grid box or Lagrangian particle tracking methods using turbulence models (not suitable for real time emergency response computation), above canopy. Input from obstacle or continuum scale data (for local sources). Upwind data for distant sources. 

To analyze the individual heat transfer kinetics of droplet clusters within the spray of twin-fluid atomizers, the local correlations between the droplet concentration and the heat and flow conditions are evaluated. Numerical simulations of the spray flow analyzed in this paper have been carried out with Large-Eddy-Simulation (LES) models with Lagrangian particle tracking (discrete particle method) for the droplet motion. A synthetic perturbation generator [30] for the inflow conditions for the gas flow and simple perturbations are added to the dispersed phase to induce realistic vortex patterns at the nozzle and in the consequent spray. 

In order to obtain a correlation, the outflow of the effervescent spray was simulated by a numerical model based on the Navier-Stokes equations and the particle tracking method. The external gas flow was considered turbulent. In droplet phase modeling, Lagrangian approach was followed. Droplet primary and secondary breakup were considered in their model. Secondary breakup consisted of cascade atomization, droplet collision, and coalescence. The droplet mean diameter under different operating conditions and liquid properties were calculated for the spray SMD using the curve fitting technique [43] ... 

The development of the Lagrangian models has been limited mainly by the inherent need for large computing capacity to carry out statistical averaging and computation of the phase interactions. The Lagrangian models are particularly applicable to very dilute or discrete flow situations for which multifluid models are not appropriate, or to situations in which the historic tracking of particles is important (such as in pulverized coal combustion in a furnace or the tracking of radioactive particles in gas-solid flows). 

The main advantage of the Eulerian-Lagrangian formulation comes from the fact that each individual bubble is modeled, allowing consideration of additional effects related to bubble-bubble and bubble-liquid interactions. Mass transfer with and without chemical reaction, bubble coalescence, and redispersion, in principle, can be added directly to an Eulerian-Lagrangian hydrodynamic model. The main disadvantage of the Eulerian-Lagrangian approach is that only a limited number of particles (bubbles) can be tracked, such as when the superficial gas velocity is low (Chen et al., 2005), due to computer limitations. 

Marker and Cell (MAC) Method The first method capable of modeling gas-hquid flows, separated by a moving interface, was the MAC of Harlow and Welch [4]. In the MAC method, as shown in Fig. 2b, the massless markers are used to define the location and track the movement of fi ee surface. This is in fact a combination of a Eulerian solution of the basic flow field, with Lagrangian tracking of marker particles. The computational cycle in the MAC method consists of the advancement of discrete field variables fi om an initial time to to the subsequent time to + At by accomplishing the steps below. 

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