Study of a single coarse bubble behavior in the presence of D.C. electric field

• Effect of DC electric field on behavior of coarse bubble was studied experimentally.
• Experimental results were extracted by digital processing of high speed video images.
• Electric forces are negligible in comparison with high hydrodynamic instability.
• EHD flow as the dominant factor was employed to manipulate bubble motion

An experimental study was carried out to investigate the effects of both uniform and non uniform D.C. electric fields on the motion and deformation of a single coarse bubble rising in dielectric liquid media. Bubble shape, aspect ratio, rising path, rise velocity and maximum inclination angle were determined by digital processing of high speed video images (600 fps). Three different viscosities of silicone oil were utilized as a base of quiescence media. Results show that the bubble deformation under the influence of electric field increases at low Re number. Moreover bubble deviation from its rising path increases by adding to electric field strength as well as reduction in liquid viscosity and subsequently the more inclination angle is observed. Bubble velocity in the region of steady and unsteady motion is not affected by applied electric field due to high hydrodynamic forces associated with relatively large bubble; though, its detachment is improved by the applied electric field. Our observations revealed that in the case of coarse bubbles, where electric forces are negligible in comparison with high hydrodynamic instability, EHD flow plays an important role in controlling the motion. This investigation can be helpful in giving a better insight of coarse bubble's behavior under the influence of electric fields and also provides a means for its manipulation in scientific problems as well as engineering applications

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