engleski

Simulating Non-Newtonian Droplet Formation With A Moving-Mesh Method

Direct interface tracking has recently matured to where it is a useful tool for simulating the fundamental physics of jet evolution and jet formation. This technique is anticipated to be very helpful in understanding the physics of ink-jet printing, where increased ink concentrations will create significant non-Newtonian behavior. A revised scheme for simulating the growth and pinching of a non-Newtonian liquid jet is described and demonstrated in this paper. Similar to some past efforts, the mesh moves with the liquid interface in a Lagrangian manner. There is no smearing or reconstruction of the interface. In the interior of the fluids, away from the interface, the vertex motion is calculated using a decomposition technique based on a finite-element method. The equations that govern the mesh motion are calculated quite cheaply using a conjugate-gradient solver. The conservation of mass, momentum, and energy are solved for the general case of moving, deforming control volumes. The mesh also changes connectivity as needed using a combination of edge contraction, face splitting, and edge flipping. The solution of the Navier-Stokes equations uses a PISO-based method and includes heat transfer as a passive scalar. An advanced C++ framework based on OpenFOAM assists with managing code complexity and promoting code reuse. Future work will include effects of temperature on properties. The non-Newtonian effects are modeled with a Bird-Carreau approach. On-going efforts will include Marangoni stresses and thermal effects on properties.

Non-Newtonian Droplet; Finite volume method; Moving mesh; OpenFOAM

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