Interfacial dynamics of stationary gas bubbles in flows in inclined tubes

Abstract

We have experimentally examined the effects of bubble size (0.4 [les ] λ [les ] 2.0), inclination angle (0° [les ] α [les ] 90°), and tube material on suspended gas bubbles in flows in tubes for a range of Weber (0 [les ] We [les ] 3.6), Reynolds (0 [les ] Re [les ] 1200), and Froude (0 [les ] Frα [les ] 1) numbers. Flow rates and associated pressure differences which allow the suspension of bubbles in glass and acrylic tubes are measured. Due to contact angle hysteresis, bubbles which dry the tube wall (i.e. form a gas–solid interface) may remain suspended over a range of flows while non-drying bubbles remain stationary for a single flow rate depending on experimental conditions. Stationary bubbles increase the axial pressure gradient with larger bubbles and steeper inclination angles leading to the greatest increase in the pressure gradient. Both the suspension flow range and pressure difference modifications are strongly dependent upon gas/liquid/solid material interactions. Stronger contact forces, i.e. smaller spreading coefficients, cause dried bubbles in acrylic tubes to remain stationary over a wider range of suspension flows than bubbles in glass tubes. Bubble deformation is governed by the interaction of interfacial, contact, and flow-derived forces. This investigation reveals the importance of bubble size, tube inclination, and tube material on gas bubble suspension.

Biomimetic Dextran Coatings On Silicon Wafers: Thin Film Properties And Wetting

“…in which vital organ blood flow can be compromised by microvascular gas embolism where a gas bubble blocks a thin blood vessel. The molecular mechanical basis of bubble adhesion to the vessel wall causing blood flow obstruction is basically unknown; our preliminary experiments [9] suggest though that blood flow obstruction is caused by adhesion of the bubble surface to the endothelial glycocalyx. If surface-surface interactions between the endothelial glycocalyx and the bubble interface control bubble adhesion, and thus determine microcirculatory blood flow and resultant organ injury, the surface roughness of an artificial blood vessel will directly impact the contact angle of gas bubbles and will then become an essential feature.…”

Wetting Characteristics of Aqueous Surfactant-Laden Drops

“…• , and not including the data for SDS on stainless steel, the hysteresis curves generally collapse to a single linear relationship closely approximated by cos φ r − cos φ a = φ a 110 − 0.14, [5] in which φ a is given in degrees. Considering only the data for which φ a ≤ 50…”

“…Dark solid line is the least-squares fit linear regression for advancing contact angles ≤50 • , given by Eq. [5].…”

“…Microvascular gas embolism occurring in the brain is a common, yet undesirable, consequence of the extracorporeal circulation required to perform many types of cardiac surgery (3). Gas bubbles enter and lodge within the circulatory system (4), and their successful displacement from blood vessels depends on overcoming the adhesion forces along the contact line (5). Modification of wetting by the addition of surfactants to alter the contact dynamics is one potential therapeutic approach.…”

A front tracking method for a deformable intravascular bubble in a tube with soluble surfactant transport

“…Some recent contributions in this area include those of Cavanagh and Eckmann [5] on stationary gas bubbles in Newtonian flows in an inclined tube and Tsai and Miksis [42] study on the dynamics of a drop in a constricted capillary fluid filled tube using a boundary integral method. Sussman and Puckett [39] have described a coupled level set/volume-of-fluid (CLSVOF) method and have, among other examples, demonstrated the capability of the method to compute the steady rise of an axisymmetric gas bubble rising in a viscous liquid with a density ratio is 714:1 and a viscosity ratio of 6667:1.…”