116 research outputs found
Direct numerical simulation of an atomizing biodiesel jet: Impact of fuel properties on atomization characteristics
[EN] The utilization of biodiesel is an effective approach to reduce pollution from internal combustion engines and thus
has attracted steadily increasing interest in the recent years. As the viscosity of biodiesel is much higher than that of
standard diesel, the atomization characteristics of a biodiesel jet can significantly deviate from those of a standard
diesel jet under identical injection conditions. Since atomization of the injected fuel has a strong impact on fuel-air
mixing and the following combustion processes, it is important to investigate the atomization of biodiesel and in
particular to understand how the fuel properties affect the atomization process and the resulting spray characteristics.
In the present study, three-dimensional direct numerical simulations are conducted to investigate atomizing
biodiesel and diesel jets. The novel adaptive multiphase solver Basilisk is used for simulations. The statistics of
droplets formed in the biodiesel jet is compared to the diesel jet under identical injection conditions.This project has been supported by the ANR MODEMI project (ANR-11-MONU-0011) program. This work was granted access to the HPC resources of TGCC-CURIE under the allocations x20152b7325, x20162b7325 and t20162b7760 made by GENCI. We would also acknowledge support from the Academic and Research Computing Services at the Baylor University.Ling, Y.; Legros, G.; Popinet, S.; Zaleski, S. (2017). Direct numerical simulation of an atomizing biodiesel jet: Impact of fuel properties on atomization characteristics. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 370-377. https://doi.org/10.4995/ILASS2017.2017.5035OCS37037
Planar Jet Stripping of Liquid Coatings: Numerical Studies
In this paper, we present a detailed example of numerical study of flm
formation in the context of metal coating. Subsequently we simulate wiping of
the film by a planar jet. The simulations have been performed using Basilisk, a
grid-adapting, strongly optimized code. Mesh adaptation allows for arbitrary
precision in relevant regions such as the contact line or the liquid-air impact
zone, while coarse grid is applied elsewhere. This, as the results indicate, is
the only realistic approach for a numerical method to cover the wide range of
necessary scales from the predicted film thickness (tens of microns) to the
domain size (meters). The results suggest assumptions of laminar flow inside
the film are not justified for heavy coats (liquid zinc). As for the wiping,
our simulations supply a great amount of instantaneous results concerning
initial film atomization as well as film thickness.Comment: 20 pages, 20 figure
An Edge-based Interface Tracking (EBIT) Method for Multiphase-flows Simulation with Surface Tension
We present a novel Front-Tracking method, the Edge-Based Interface Tracking
(EBIT) method for multiphase flow simulations. In the EBIT method, the markers
are located on the grid edges and the interface can be reconstructed without
storing the connectivity of the markers. This feature makes the process of
marker addition or removal easier than in the traditional Front-Tracking
method. The EBIT method also allows almost automatic parallelization due to the
lack of explicit connectivity.
In a previous journal article we have presented the kinematic part of the
EBIT method, that includes the algorithms for interface linear reconstruction
and advection. Here, we complete the presentation of the EBIT method and
combine the kinematic algorithm with a Navier--Stokes solver. To identify the
reference phase and to distinguish ambiguous topological configurations, we
introduce a new feature: the Color Vertex. For the coupling with the
Navier--Stokes equations, we first calculate volume fractions from the position
of the markers and the Color Vertex, then viscosity and density fields from the
computed volume fractions and finally surface tension stresses with the
Height-Function method. In addition, an automatic topology change algorithm is
implemented into the EBIT method, making it possible the simulation of more
complex flows. A two-dimensional version of the EBIT method has been
implemented in the open-source Basilisk platform, and validated with five
standard test cases: (1) translation with uniform velocity, (2) single vortex,
(3) capillary wave, (4) Rayleigh-Taylor instability and (5) rising bubble. The
results are compared with those obtained with the Volume-of-Fluid (VOF) method
already implemented in Basilisk
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