Drop formation from a capillary tube: Comparison of different bulk fluid on Newtonian drops and formation of Newtonian and non-Newtonian drops in air using image processing

• Published in: International journal of heat and mass transfer Vol. 124; pp. 912 - 919
• Main Authors: Nazari, Ashkan, Zadkazemi Derakhshi, Amin, Nazari, Arash, Firoozabadi, Bahar
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2018; Elsevier BV
• Subjects: Capillary tube; Capillary tubes; Carboxymethyl cellulose; Cellulose; Drop formation; Fluids; High speed; High speed cameras; Image processing; Newtonian; Newtonian fluids; Non Newtonian fluids; Non-Newtonian; Properties (attributes); Toluene; Water drops; Drop formation; Newtonian; Non-Newtonian; Image processing; Capillary tube
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2018.04.024

•120° maximum contact angle of water drops in different continuous phases.•Observation of the wetted diameter from inner to outer diameter of the capillary.•Considerable variation of the drop’s behavior with CMC solution’s concentration.•Nearly the same behavior of water drops in toluene and n-hexane versus drops in air. The formation of water drops as a Newtonian fluid and formation of a shear-thinning non-Newtonian fluid, Carboxyl Methyl Cellulose (CMC) from a capillary into different bulk fluids are experimentally investigated. A high speed camera is used to visualize the images of the drops and an image-processing code employed to determine the drop properties from each image. It was found that the properties of the water drops when they are drooped into the liquids bulk fluids such as toluene and n-hexane are almost the same while they differed substantially when they were drooped into the air bulk fluid. It is shown that during the formation of water drop in all three kinds of bulk fluids, the drop forms from the inner diameter of the needle and it moves toward the outer diameter. In addition, the properties of a low-concentration CMC in the air was almost identical to the properties of water drops, however the high-concentration CMC shows significant variations as compared to the both low-concentration CMC and water drops.