scholarly journals On an evaluation of the drag force of a growing vapor bubble at rectilinear accelerated ascension

2002 ◽  
pp. 103-114 ◽  
Author(s):  
Radomir Askovic
Keyword(s):  
Drag Coefficient ◽  
Drag Force ◽  
Vapor Bubble ◽  
Bubble Growth ◽  
Simple Relation ◽  
Heat Diffusion ◽  
Diffusion Controlled

By applying the in viscid approximation, a simple relation for predicting the drag coefficient of a growing vapor bubble at rectilinear accelerated ascension in uniformly-superheated pure liquids was developed. The relation is valid in both regions: inertia controlled and heat diffusion controlled bubble growth, respectively. The drag coefficient decreases with time for all accelerations, as well as with augmentation of the bubble acceleration at each instant of time, independently of the internal vapor parameters.

scholarly journals Drag of a growing bubble at rectilinear accelerated ascension in pure liquids and binary solutions

2003 ◽  
pp. 177-192 ◽  
Author(s):  
Radomir Askovic
Keyword(s):  
Surface Tension ◽  
General Solution ◽  
Drag Coefficient ◽  
Critical Radius ◽  
Heat Diffusion ◽  
Binary Solutions ◽  
Diffusion Controlled

The problem of predicting the drag coefficient of a growing bubble at rectilinear accelerated ascension in uniformly super?heated pure liquids and in binary solutions with a non-volatile solute at large Reynolds and Peclet numbers is discussed. In the case of pure liquids, the general solution for the drag coefficient of an accelerated growing bubble from its inception at the critical radius and through the surface-tension-, inertia-, and heat-diffusion-controlled regimes is established, as well as some necessary adaptations in the case of binary solutions with a non-volatile solute. Two particular limiting regimes in the case of pure liquids, inertia-controlled and heat-diffusion-controlled regimes, respectively, are analyzed in details, with satisfactory results. .

Numerical Solution for the Spherical Bubble Growth Problem in a Uniformly Ultraheated Liquid

1977 ◽  
Vol 19 (3) ◽  
pp. 101-107 ◽  
Author(s):  
T. Saitoh ◽  
A. Shima
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Bubble Growth ◽  
Growth Conditions ◽  
Heat Diffusion ◽  
Controlled Growth ◽  
Spherical Bubble ◽  
Diffusion Controlled ◽  
Wide Range ◽  
Growth Problem

A multi-point, implicit-type, finite-difference method for solving the bubble growth (or collapse) problem in an ultraheated liquid is proposed. The method is applicable to both inertia-controlled growth and heat-diffusion-controlled growth. The results are compared with several asymptotic solutions, involving Plesset-Zwick and Mikic-Rohsenow-Griffith solutions. Present results strongly support the Mikic-Rohsenow-Griffith solution for the wide range of bubble growth conditions, e.g. given fluids, pressure, liquid ultraheat, etc.

Aerodynamics of Cyclist Posture, Bicycle and Helmet Characteristics in Time Trial Stage

2012 ◽  
Vol 28 (3) ◽  
pp. 317-323 ◽  
Author(s):  
Vincent Chabroux ◽  
Caroline Barelle ◽  
Daniel Favier
Keyword(s):  
Statistical Analysis ◽  
Wind Tunnel ◽  
Drag Coefficient ◽  
Drag Force ◽  
Time Trial ◽  
Frontal Area ◽  
Significant Gain ◽  
Upper Limbs ◽  
Force Coefficient ◽  
Coefficient Reduction

The present work is focused on the aerodynamic study of different parameters, including both the posture of a cyclist’s upper limbs and the saddle position, in time trial (TT) stages. The aerodynamic influence of a TT helmet large visor is also quantified as a function of the helmet inclination. Experiments conducted in a wind tunnel on nine professional cyclists provided drag force and frontal area measurements to determine the drag force coefficient. Data statistical analysis clearly shows that the hands positioning on shifters and the elbows joined together are significantly reducing the cyclist drag force. Concerning the saddle position, the drag force is shown to be significantly increased (about 3%) when the saddle is raised. The usual helmet inclination appears to be the inclination value minimizing the drag force. Moreover, the addition of a large visor on the helmet is shown to provide a drag coefficient reduction as a function of the helmet inclination. Present results indicate that variations in the TT cyclist posture, the saddle position and the helmet visor can produce a significant gain in time (up to 2.2%) during stages.

Effect of Pressure on Bubble Growth Within Liquid Droplets at the Superheat Limit

1982 ◽  
Vol 104 (4) ◽  
pp. 750-757 ◽  
Author(s):  
C. T. Avedisian
Keyword(s):  
Vapor Bubble ◽  
Bubble Growth ◽  
High Speed ◽  
Ambient Pressure ◽  
Organic Liquid ◽  
Liquid Droplets ◽  
Growth Data ◽  
Two Phase ◽  
Photographic Evidence ◽  
Good Agreement

A study of high-pressure bubble growth within liquid droplets heated to their limits of superheat is reported. Droplets of an organic liquid (n-octane) were heated in an immiscible nonvolatile field liquid (glycerine) until they began to boil. High-speed cine photography was used for recording the qualitative aspects of boiling intensity and for obtaining some basic bubble growth data which have not been previously reported. The intensity of droplet boiling was found to be strongly dependent on ambient pressure. At atmospheric pressure the droplets boiled in a comparatively violent manner. At higher pressures photographic evidence revealed a two-phase droplet configuration consisting of an expanding vapor bubble beneath which was suspended a pool of the vaporizing liquid. A qualitative theory for growth of the two-phase droplet was based on assuming that heat for vaporizing the volatile liquid was transferred across a thin thermal boundary layer surrounding the vapor bubble. Measured droplet radii were found to be in relatively good agreement with predicted radii.

Simulation of Sphere’s Motion Induced by Shock Waves

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Dan Igra ◽  
Ozer Igra ◽  
Lazhar Houas ◽  
Georges Jourdan
Keyword(s):  
Shock Waves ◽  
Drag Coefficient ◽  
Drag Force ◽  
Stationary Flow ◽  
Experimental Results ◽  
Experimental Findings ◽  
Sphere Drag ◽  
Simulation Scheme ◽  
Good Agreement

Simulations of experimental results appearing in Jourdan et al. (2007, “Drag Coefficient of a Sphere in a Non-Stationary Flow: New Results,”Proc. R. Soc. London, Ser. A, 463, pp. 3323–3345) regarding acceleration of a sphere by the postshock flow were conducted in order to find the contribution of the various parameters affecting the sphere drag force. Based on the good agreement found between present simulations and experimental findings, it is concluded that the proposed simulation scheme could safely be used for evaluating the sphere’s motion in the postshock flow.

Vapor bubble growth in heterogeneous boiling—I. Formulation

1995 ◽  
Vol 38 (5) ◽  
pp. 909-919 ◽  
Author(s):  
Renwei Mei ◽  
Wenchin Chen ◽  
James F. Klausner
Keyword(s):  
Vapor Bubble ◽  
Bubble Growth

Vapor bubble growth at the surface of flat and cylindrical heaters

2008 ◽  
Vol 17 (3) ◽  
pp. 227-234 ◽  
Author(s):  
S. P. Aktershev ◽  
V. V. Ovchinnikov
Keyword(s):  
Vapor Bubble ◽  
Bubble Growth
Sign in / Sign up

Export Citation Format

Share Document