10,041 research outputs found
Numerical Simulations of Bouncing Jets
Bouncing jets are fascinating phenomenons occurring under certain conditions
when a jet impinges on a free surface. This effect is observed when the fluid
is Newtonian and the jet falls in a bath undergoing a solid motion. It occurs
also for non-Newtonian fluids when the jets falls in a vessel at rest
containing the same fluid.
We investigate numerically the impact of the experimental setting and the
rheological properties of the fluid on the onset of the bouncing phenomenon.
Our investigations show that the occurrence of a thin lubricating layer of air
separating the jet and the rest of the liquid is a key factor for the bouncing
of the jet to happen.
The numerical technique that is used consists of a projection method for the
Navier-Stokes system coupled with a level set formulation for the
representation of the interface. The space approximation is done with adaptive
finite elements. Adaptive refinement is shown to be very important to capture
the thin layer of air that is responsible for the bouncing
On the role of particles and radial basis functions in a finite element level set method for bubble dynamics
The aim of this presentation is to highlight the role that Particle-based
simulations and Radial Basis Functions (RBFs) have played in the development of a computationally efficient, level-set, Finite Element method for the simulation of Newtonian and non-Newtonian interface flows. First, we introduce the mathemat- ical formulation and the interface-capturing technique used in the simulation of multiphase flows, underscoring the influence of marker particles on the enhanced definition of the interface. Then, we explore the effect of adding polymer parti- cles to the domain to perform Brownian Dynamics Simulations of polymer flows. Finally, we leverage RBFs to reconstruct, in an almost free-independent way the polymer stress tensor retrieved from the polymer particles.
Numerical simulations of pure advection flows and bubble dynamics simulations of complex flows on two-dimensional configurations emphasize the improvements
offered by this hybrid, Finite Element/RBF/Particle-based method
Simplex space-time meshes in thermally coupled two-phase flow simulations of mold filling
The quality of plastic parts produced through injection molding depends on
many factors. Especially during the filling stage, defects such as weld lines,
burrs, or insufficient filling can occur. Numerical methods need to be employed
to improve product quality by means of predicting and simulating the injection
molding process. In the current work, a highly viscous incompressible
non-isothermal two-phase flow is simulated, which takes place during the cavity
filling. The injected melt exhibits a shear-thinning behavior, which is
described by the Carreau-WLF model. Besides that, a novel discretization method
is used in the context of 4D simplex space-time grids [2]. This method allows
for local temporal refinement in the vicinity of, e.g., the evolving front of
the melt [10]. Utilizing such an adaptive refinement can lead to locally
improved numerical accuracy while maintaining the highest possible
computational efficiency in the remaining of the domain. For demonstration
purposes, a set of 2D and 3D benchmark cases, that involve the filling of
various cavities with a distributor, are presented.Comment: 14 pages, 11 Figures, 4 Table
Finite element methods for deterministic simulation of polymeric fluids
In this work we consider a finite element method for solving the coupled Navier-Stokes (NS) and Fokker-Planck (FP) multiscale model that describes the dynamics of dilute polymeric fluids. Deterministic approaches such as ours have not received much attention in the literature because they present a formidable computational challenge, due to the fact that the analytical solution to the Fokker-Planck equation may be a function of a large number of independent variables. For instance, to simulate a non-homogeneous flow one must solve the coupled NS-FP system in which (for a 3-dimensional flow, using the dumbbell model for polymers) the Fokker-Planck equation is posed in a 6-dimensional domain. In this work we seek to demonstrate the feasibility of our deterministic approach. We begin by discussing the physical and mathematical foundations of the NS-FP model. We then present a literature review of relevant developments in computational rheology and develop our deterministic finite element based method in detail. Numerical results demonstrating the efficiency of our approach are then given, including some novel results for the simulation of a fully 3-dimensional flow. We utilise parallel computation to perform the large-scale numerical simulations
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