Numerical study on magnetic nanofluid (MNF) film boiling in non-uniform magnetic fields generated by current carrying wires

2022 ◽  
Vol 175 ◽  
pp. 107461
Author(s):  
Fucheng Chang ◽  
Yuhao Shang ◽  
He Hu ◽  
Xi Li ◽  
Kaikai Guo ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Numerical Study ◽  
Film Boiling ◽  
Magnetic Nanofluid

Numerical Study of the Effect of Magnetic Fields on Melt-Crystal Interface-Deflection in Czochralski Crystal Growth

2003 ◽  
Author(s):  
Lijun Liu ◽  
Koichi Kakimoto
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Numerical Study ◽  
Silicon Crystal ◽  
Czochralski Growth ◽  
Thermal Flow ◽  
Interface Shape ◽  
Convective Thermal ◽  
And Control ◽  
Crystal Interface

In order to control the impurity distribution and remove defects in a crystal grown in Czochralski growth for high quality crystals of silicon, it is necessary to study and control the melt-crystal interface shape, which plays an important role in control of the crystal quality. The melt-crystal interface interacts with and is determined by the convective thermal flow of the melt in the crucible. Application of magnetic field in the Czochralski system is an effective tool to control the convective thermal flow in the crucible. Therefore, the shape of the melt-crystal interface can be modified accordingly. Numerical study is performed in this paper to understand the effect of magnetic field on the interface deflection in Czochralski system. Comparisons have been carried out by computations for four arrangements of the magnetic field: without magnetic field, a vertical magnetic field and two types of cusp-shaped magnetic field. The velocity, pressure, thermal and electromagnetic fields are solved with adaptation of the mesh to the iteratively modified interface shape. The multi-block technique is applied to discretize the melt field in the crucible and the solid field of silicon crystal. The unknown shape of the melt-crystal interface is achieved by an iterative procedure. The computation results show that the magnetic fields have obvious effects on both the pattern and strength of the convective flow and the interface shape. Applying magnetic field in the Czochralski system, therefore, is an effective tool to control the quality of bulk crystal in Czochralski growth process.

Numerical Study of Natural Convection in Vertical Cylindrical Annular Enclosure Filled with Cu-Water Nanofluid under Magnetic Fields

2019 ◽  
Vol 392 ◽  
pp. 123-137 ◽  
Author(s):  
Mohamed A. Medebber ◽  
Abderrahmane Aissa ◽  
Mohamed El Amine Slimani ◽  
Noureddine Retiel
Keyword(s):  
Natural Convection ◽  
Magnetic Fields ◽  
Volume Fraction ◽  
Numerical Study ◽  
Physical Parameters ◽  
Cold Temperatures ◽  
Simpler Algorithm ◽  
Wide Range ◽  
Nanoparticles Volume Fraction ◽  
Volume Method

The two dimensional study of natural convection in vertical cylindrical annular enclosure filled with Cu-water nanofluid under magnetic fields is numerically analyzed. The vertical walls are maintained at different uniform hot and cold temperatures, THand TC, respectively. The top and bottom walls of the enclosure are thermally insulated. The governing equations are solved numerically by using a finite volume method. The coupling between the continuity and momentum equations is effected using the SIMPLER algorithm. Numerical analysis has been carried out for a wide range of Rayleigh number (103≤Ra≤106), Hartmann number (1 ≤Ha≤100) and nanoparticles volume fraction (0 ≤φ≤0.08). The influence of theses physical parameters on the streamlines, isotherms and average Nusselt has been numerically investigated.

Interaction of Asymmetric Films Around Boiling Cylinder Array: Homogeneous Interface to Chaotic Phenomenon

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Akash Deep ◽  
Chandan Swaroop Meena ◽  
Arup Kumar Das
Keyword(s):  
Source Term ◽  
Film Growth ◽  
Numerical Study ◽  
Film Boiling ◽  
Water Pool ◽  
Time Interaction ◽  
Saturated Water ◽  
Finite Volume Discretization ◽  
Horizontal Cylinders ◽  
Four Cylinders

We report numerical study of film boiling around hot and horizontal cylinders in a saturated water pool to establish interfacial interactions leading toward dryout. Volume of fluid-based finite-volume discretization is performed in the domain for incorporation of source term in mass momentum and energy conservation equations due to phase change. At first, film boiling around single cylinder is simulated at different surface temperatures to understand unconstrained film growth and subsequent film bubble release due to buoyancy. Using velocity vectors and temperature contours, effect of film flow dynamics on bubble departure is depicted. This study has been extended further with multiple cylinders in three different stacking arrangements in order to understand the interaction of films in vicinity. Vertical interaction between cylinders leads to suppression of bubble release at the lower cylinder in comparison to the upper one. In the case of horizontal interactions, bubbles attract each other and merge, provided favorable pitch between cylinders and temperatures of the surfaces is maintained. Offset four cylinders stack maintaining vertical and horizontal pitch allows both lateral vapor affinity and bubble suppression in the lower most cylinder simultaneously. With time interaction of accumulated vapor films around cylinders hinders replenishment of fresh liquid to the hot surfaces leading toward chaotic phenomena or dryout in boiling heat transfer.

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