Manipulation of bubble migration through thermal capillary effect under variable buoyancy

Dynamics of double bubbles under the driving of burst ultrasound

“…That makes cavitation being widely used in all kinds of fields, such as therapy [6] , catalyzing [7] , wastewater treatment [8] and parts cleaning [9] . Moreover, bubbles can be used in material processing in the reduced gravity environment [10] and drugs delivery for tissues [11] if they can be manipulated. Exploring the dynamics of bubbles is of great significance for the application of them.…”

Numerical Studies on the Controlled Thermocapillary Migration of a Sessile Droplet

“…7 Besides the external forces, the thermocapillary force may be utilized for droplet manipulation, which is caused by the nonuniform interfacial tension force due to the temperature gradient. 8,9 For example, when a sessile droplet is deposited on a nonuniformly heated substrate, the nonuniform temperature distribution can cause the tangential thermocapillary force along the interface, forming the Marangoni flow and driving the droplet migration along the substrate. 10−13 It is well-known that the migration of suspended droplet under the temperature gradient is toward the hot region; it was previously believed that a sessile droplet on a nonuniformly heated substrate would move toward the cold region.…”

“…The dependence of surface tension on the temperature can be described as σ(T) = σ 0 − σ T (T − T 0 ), where σ 0 is the surface tension at reference temperature T 0 and σ T is the surface tension variation rate over temperature. 21,32 The imbalanced surface tension near the contact line can cause the mechanical force F cl = σ h cos θ − σ c cos θ, where σ h is the surface tension near the contact line at the hot region and σ c is the surface tension near the contact line at the cold region. The mechanical force is determined by the temperature gradient and contact angle, and its direction can be changed by the contact angle.…”

“…The controlled migration of sessile droplet can be achieved through gravity, magnetic force, electric force, etc . Besides the external forces, the thermocapillary force may be utilized for droplet manipulation, which is caused by the nonuniform interfacial tension force due to the temperature gradient. , For example, when a sessile droplet is deposited on a nonuniformly heated substrate, the nonuniform temperature distribution can cause the tangential thermocapillary force along the interface, forming the Marangoni flow and driving the droplet migration along the substrate. − …”

“…It is well-known that the migration of suspended droplet under the temperature gradient is toward the hot region; it was previously believed that a sessile droplet on a nonuniformly heated substrate would move toward the cold region. , Bouasse , observed the droplet migration toward the cold region of a nonuniformly heated wire. Through the lubrication theory, Ford and Nadim analyzed the thermocapillary migration of droplet at low contact angles and found that the sessile droplet moved toward the cold region of the solid substrate.…”