RT Journal Article
ID 5e8359ca61aeab58
A1 van der Geld, Cees W. M.
T1 SHAPE OSCILLATIONS OF A BOILING BUBBLE
JF Multiphase Science and Technology
JO MST
YR 2010
FD 2010-06-30
VO 22
IS 2
SP 157
OP 175
K1 bubble oscillations
K1 contact angle
K1 Euler-Lagrange
K1 generalized forces
K1 interfacial forces
K1 stability analysis
K1 PIV
K1 added mass
AB The shape of a free bubble or of a boiling bubble at an artificial cavity or needle may exhibit strong, axisymmetric shape oscillations. The Euler-Lagrangian approach facilitates computation of such oscillations. A derivation of the generalized forces needed in such an approach is presented. This derivation eliminates ambiguity in the description of the driving forces involved. Both increasing amplitude of oscillation and decreasing distance to the wall lower the radian frequency of oscillation of a free bubble. These two effects are quantified. A two-equation model to predict growth and detachment of a bubble with the shape of a truncated sphere on a plane wall is derived with the Euler-Lagrange approach. The period of oscillation of a fundamental mode of a free bubble, T_{osc}, is known to be proportional to the initial radius, R, cubed. That of a boiling bubble attached to a cavity has a similar dependency but with a difference in the proportionality constant of nearly a factor 2. This factor can be explained with the aid of a stability analysis of the two-equation model for a truncated sphere. The high factor results from the combination of two added mass force contributions: one related to isotropic deformation (expansion and contraction), the other related to motion of the center of mass above the plane wall. The amplitude of the oscillatory motion of a boiling bubble at a wall can be large during a long time of observation, e.g., a quarter of a second. Some dedicated experiments reveal the source of kinetic energy of this motion.
PB Begell House
LK http://dl.begellhouse.com/journals/5af8c23d50e0a883,2ace4ef415ce34d2,5e8359ca61aeab58.html