Convective heat transfer from two rotating circular cylinders in tandem arrangement by using lattice Boltzmann method

Abstract

The numerical investigation of the two-dimensional laminar flow past two rotating circular cylinders in the tandem arrangement is conducted by the lattice Boltzmann method. The numerical strategy is used for dealing with curved and moving boundaries of the second-order accuracy for velocity and temperature fields. The effects of various rotational speed ratios and gap spacing are studied with the Reynolds number of 100 and the Prandtl number of 0.71. A varied range of rotational speed ratios are investigated for four different gap spacing, i.e., 3.0, 1.5, 0.7, and 0.2. The results show that, for the first cylinder, the lift and drag coefficients for large gap spacing are similar to those for a single cylinder; for the second cylinder, the lift coefficient descends with the increase in the angular velocity for all gap spacing, while the drag coefficient ascends except for the gap spacing of 3.0. The results of the averaged periodic Nusselt number on the surface of the cylinders show that, for small distances between the cylinders and low angular velocities, conduction is a dominant mechanism of heat transfer, but for large distances and high angular velocities, convection is the main mechanism of heat transfer.

Analysis of the thermo-fluidic transport around counter-rotating tandem circular cylinders

“…Sohankar et al 57 reported that a blockage ratio of less than or equal to 5% mimics an almost infinite or unconfined domain with a little effect of the artificial confining boundaries on the flow characteristics near the cylinder. There are also some numerical works reported in the literature for rotating 32 or tandem cylinders 58 carried out using a similar computational domain. In the present work, the dimensionless spacing (g*) between the cylinders is kept fixed as g* ¼ 1.5.…”

“…However, the critical rotational speed depends on the parameters including Re and g*. [30][31][32][33] The role of rotation and the cylinder spacing on the flow behavior are contradictory in nature, while the rotation tries to stabilize the flow, the cylinder spacing destabilizes it. The forced convection heat transfer over co-rotating/counter-rotating cylinders arranged in tandem or side-by-side configurations are analyzed in.…”

Effect of downstream cylinder rotation on wake dynamics of two inline circular cylinders

“…Ayyappan and Vengadesan [17] investigated the influence of placing a rotating control rod at staggering angles with respect to a stationary circular cylinder for two different values of control rod diameter and fixed rotational speed. Nemati et al [18] studied flow and heat transfer for flow past two rotating circular cylinders in tandem using Lattice Boltzmann method for selected values of spacing at Re = 100. Their work clearly suggests that further investigations need to be carried out on flow control aspect of the problem.…”

Flow and roller array interaction at low Reynolds numbers

“…When the cylinders are further separated, both cylinders co-shed vortices and their interference weakens substantially (Jo et al 2002). Nemati et al (2012) studied the flow over two rotating tandem cylinders at low Reynolds number. It shows that the flow is strongly influenced by the separating distance and the tangential speed.…”