scholarly journals Numerical study of the onset of thermosolutal convection in rotating spherical shells

2012 ◽  
Vol 24 (6) ◽  
pp. 064101 ◽  
Author(s):  
Marta Net ◽  
Ferran Garcia ◽  
Juan Sánchez
Keyword(s):  
Numerical Study ◽  
Thermosolutal Convection ◽  
Spherical Shells

Experimental and Numerical Study on the Dynamic Buckling of Ping-pong Balls under Impact Loading

2012 ◽  
Vol 13 (1) ◽  
Author(s):  
X. W. Zhang ◽  
T. X. Yu
Keyword(s):  
Impact Loading ◽  
Numerical Study ◽  
Digital Camera ◽  
Dynamic Buckling ◽  
Spherical Shells ◽  
Static Tests ◽  
Air Gun ◽  
Ping Pong ◽  
The Impact ◽  
Force Displacement

AbstractBy means of ping-pong balls, the dynamic buckling behaviours of thin-walled spherical shells under impact loading are studied both experimentally and numerically. First, the quasi-static tests were conducted on an MTS tester, in which the ball was compressed onto a PMMA plate. Apart from the force-displacement relationship, the evolution of the contact zone between the ball and the plate was obtained by a digital camera. In the impact tests, ping-pong balls were accelerated by an air-gun and then impinged onto a rigid plate with the velocity ranging 10–45 m

NUMERICAL STUDY OF LAMINAR CONVECTION AND THERMOSOLUTAL CONVECTION IN A TWO-DIMENSIONAL TRAPEZOIDAL CAVITY

1994 ◽  
Vol 18 (3) ◽  
pp. 207-224 ◽  
Author(s):  
M. Lacroix
Keyword(s):  
Schmidt Number ◽  
Numerical Study ◽  
Temperature Gradients ◽  
Thermosolutal Convection ◽  
Governing Equations ◽  
Concentration Gradients ◽  
Height Ratio ◽  
Vertical Walls ◽  
Laminar Convection ◽  
Rayleigh Numbers

Heat transfer driven by temperature gradients and simultaneous temperature and concentration gradients has been studied numerically for horizontal prismatic cavities of trapezoidal section having a hot horizontal base, a cool inclined top and insulated vertical walls. Results are presented for a cavity with width-to-mean height ratio of 4, thermal and concentration Rayleigh numbers up to 106 and 5.105 respectively, and top surface inclinations from 0 to 15 deg to the horizontal. The Prandtl and the Schmidt number used are 0.71 and 0.6 respectively. The governing equations are expressed in terms of stream function and vorticity and body-fitted coordinates are used for mapping the sloping top wall. As the inclination of the top surface is increased, the Nusselt and Sherwood numbers decrease. The effect of opposing thermal and concentration gradients on the Nusselt and Sherwood numbers is however more important than the effect of the inclination of the top surface. Theoretical Nusselt and Sherwood numbers are compared with available experimental data.

scholarly journals A theoretical and numerical study of thermosolutal convection: stability of a salinity gradient solar pond

2011 ◽  
Vol 15 (1) ◽  
pp. 67-80 ◽  
Author(s):  
Dalila Akrour ◽  
Mouloud Tribeche ◽  
Djamel Kalache
Keyword(s):  
Stability Analysis ◽  
Boundary Conditions ◽  
Numerical Study ◽  
Salinity Gradient ◽  
Thermosolutal Convection ◽  
Separation Coefficient ◽  
Onset Of Convection ◽  
Solar Pond ◽  
Negative Case ◽  
The Stability

A theoretical and numerical study of the effect of thermodiffusion on the stability of a gradient layer is presented. It intends to clarify the mechanisms of fluid dynamics and the processes which occur in a salinity gradient solar pond. A mathematical modelling is developed to describe the thermodiffusion contribution on the solar pond where thermal, radiative, and massive fluxes are coupled in the double diffusion. More realistic boundary conditions for temperature and concentration profiles are used. Our results are compared with those obtained experimentally by authors without extracting the heat flux from the storage zone. We have considered the stability analysis of the equilibrium solution. We assumed that the perturbation of quantities such as velocity, temperature, and concentration are infinitesimal. Linearized equations satisfying appropriate prescribed boundary conditions are then obtained and expanded into polynomials form. The Galerkin method along with a symbolic algebra code (Maple) are used to solve these equations. The effect of the separation coefficient y is analyzed in the positive and negative case. We have also numerically compared the critical Rayleigh numbers for the onset of convection with those obtained by the linear stability analysis for Le = 100, ?a = 0.8, and f = 0.5.

Numerical Study of a Vertical Solidification Process under Magnetic Field in Unsteady State

2010 ◽  
Vol 297-301 ◽  
pp. 254-262
Author(s):  
Sabrina Nouri ◽  
Mouhamed Benzeghiba ◽  
Ahmed Benzaoui
Keyword(s):  
Magnetic Field ◽  
Binary Alloy ◽  
Numerical Study ◽  
Magnetic Field Effect ◽  
Solidification Process ◽  
Computer Code ◽  
Thermosolutal Convection ◽  
Unsteady State ◽  
Vertical Solidification ◽  
The Magnetic Field

Numerical computation is achieved in an axisymmetric configuration to analyze the magnetic field effect on thermosolutal convection during vertical solidification of a binary alloy. The bath is exposed to a uniform temperature profile in unsteady state. During the growth three regions appear: liquid, mushy and solid zones. The mushy zone is assimilated to porous medium. A mathematical model of heat, momentum and solute transfer has been developed in primitive variables (pressure-velocity). A single domain approach (enthalpy method) is used to build the equations system. In this context, a computer code has been developed and validated with previous studies. The results in term of stream function and solute concentration show the strong effect of the magnetic field on the fluid flow and on the solutal stratification. The effects of magnetic field and melt convection intensity were demonstrated. The main results show that the quality of highly doped binary alloy crystals can be improved when the growth process occurs at low pulling rates and under a magnetic field.

Numerical Study of the Thermosolutal Convection Induced Macrosegregation during Columnar Solidification

2010 ◽  
Vol 154-155 ◽  
pp. 1415-1418
Author(s):  
Jing Hao ◽  
Meng Huai Wu ◽  
Andreas Ludwig ◽  
Monika Grasser
Keyword(s):  
Numerical Model ◽  
Process Parameters ◽  
Thermophysical Properties ◽  
Numerical Study ◽  
Sensitivity Study ◽  
Thermosolutal Convection ◽  
Two Phase ◽  
Numerical Problem ◽  
Solidification Model ◽  
Comparison With Experiments

As a response to “call for contribution to a numerical problem for 2D columnar solidification of binary alloys” [Bellet et al., Int. J. Therm. Sci., Vol. 48(11)(2009), p. 2013], the macrosegregation in a Pb-18wt.%Sn benchmark casting is numerically studied with a two-phase columnar solidification model developed by the current authors. The studies were done with 2D calculations in response to the call, and a 3D calculation was performed to confirm the consistency with the 2D case. A grid-sensitivity study was done to ensure the reliability and accuracy of the present results. The segregation mechanism due to thermosolutal convection was analyzed and the uncertainties resulting from the inaccurate thermophysical properties, modelling and process parameters are discussed. The numerical model was evaluated by comparison with experiments.

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