Some of the difficulties in solving fluids that contain particles within them

  • Idelsohn, Sergio (CIMNE)
  • Gimenez, Juan (CIMNE)
  • Oñate, Eugenio (CIMNE)

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Particle-laden flows refer to a kind of two-phase fluid flow in which one of the phases is continuously connected and the other phase is made up of small immiscible particles. A wide variety of scientific and engineering applications belong to particles-laden flows, for instance dispersion of contamination in the atmosphere, fluidization in combustion processes, deposition of aerosols in aerosol drugs, spread of virus in the air, rain formation in clouds, sand and dust storms, protoplanetary disks, volcanic eruptions, geological sedimentation processes, pharmaceutical sprays, liquid-fuelled combustion and solid rocket motors, among many others. The equations governing interactions of particles with fluids in a particle-laden mixture have been known for many decades. However, their coupled dynamics often result in complex behaviour such as preferential concentration and turbulence modulation. These are still ongoing topics of research. The starting point for a mathematical description of almost any type of fluid flow is the classical set of Navier–Stokes equations (N-S). To describe particle-laden flows, these equations must be modified for the effect of the particles. Typically, the fluid is treated in a Eulerian frame, while the particles are treated in a Lagrangian way. However, problem with the Lagrangian treatment of the particles is that once the number becomes large, it may require a prohibitive amount of computational power to track a sufficiently large sample of particles required. In this presentation we propose to solve particle-laden fluid flows using the multi-scale method called Pseudo-Direct Numerical Simulation (P-DNS)to study the phenomenon of turbulence modulation and to simulate the presence of particles as a continuum function that moves within the fluid. In this way, the need to represent each of the particles that move in the fluid is avoided.