The effect of extrusion slit on the flow and heat-transfer characteristics from a continuously moving material with suction or injection

• Published in: The International journal of heat and fluid flow Vol. 21; no. 1; pp. 84 - 91
• Main Authors: Al-Sanea, Sami A., Ali, Mohamed E.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.02.2000; Elsevier Science
• Subjects: Applied fluid mechanics; Computational methods in fluid dynamics; Exact sciences and technology; Finite volume; Fluid dynamics; Fundamental areas of phenomenology (including applications); Hydrodynamics, hydraulics, hydrostatics; Nonsimilar region; Physics; Stretched surface; Suction or injection; Suction or injection; Stretched surface; Nonsimilar region; Finite volume; Temperature distribution; Nusselt number; Skin friction; Aspiration; Digital simulation; Pressure distribution; Hydrodynamics; Finite volume method; Velocity distribution; Injection; Moving wall; Extrusion; Slot; Stretching; Heat transfer
• ISSN: 0142-727X; 1879-2278
• DOI: 10.1016/S0142-727X(99)00062-4

The flow and heat-transfer characteristics over a continuously moving horizontal material with suction or injection are studied very close and far away downstream from the extrusion slit. The finite-volume method is used to map out the solutions in the nonsimilar and similar regions subject to uniform surface velocity and temperature. The effects of Prandtl number ( Pr), suction/injection parameter ( d) and Reynolds number ( Re x ) on the friction and heat-transfer coefficients are studied. Comparisons with the similarity method solutions downstream at high Re x are made. Critical Reynolds numbers to distinguish between the self-similar and nonsimilar regions are obtained. The region very close to the slit is characterized by: (i) a rapid increase in skin-friction coefficient with increasing suction, or with increasing injection above d ≈ 0.45; the lowest friction coefficient is attained at an injection parameter d ≈ 0.45, and (ii) large heat-transfer coefficient which increases with increasing Prandtl number and suction, and decreases with increasing injection. On the other hand, downstream where the similarity solution is valid both the skin-friction and heat-transfer coefficients reach asymptotic values depending on d and, for the latter, on Pr.