Laminar flow of non-Newtonian shear-thinning fluids in a T-channel

• Power-law flow characteristics in a right-angled horizontal T-channel are studied.
• Computations are reported for Re = 5–200 and n = 0.2–1.
• Length of recirculation zone increases with decreasing n for the fixed Re.
• Critical Reynolds number for the onset of flow separation decreases with decreasing n.
• A simple wake-length correlation is also established.

Flow characteristics of non-Newtonian power-law fluids in a right-angled horizontal T-channel are studied in the laminar regime. In particular, the two-dimensional numerical computations are performed using Ansys Fluent for the following range of physical parameters: Reynolds number (Re) = 5–200 and power-law index (n) = 0.2–1 (covering shear-thinning, n < 1 and Newtonian, n = 1 fluids). The flow fields have been explained by streamline contours. The engineering parameters such as wake/recirculation length, critical Reynolds number for the onset of flow separation and the variation of viscosity along the lower wall of side branch are calculated for the above range of settings by using constant density and non-Newtonian power-law viscosity model. The results showed that for a particular n, the length of recirculation zone increases in the side branch with increasing Re. Also, it increases with decreasing n for a fixed Re. The critical Reynolds number for the onset of flow separation decreases with decreasing n. A simple wake-length correlation is also established at different values of Re and n for the range of parameters.