The present study numerically investigates two-dimensional
laminar fluid flow and heat transfer past a circular cylinder under a forced oscillating normal to the free-stream flow at a fixed Reynolds number equal to 185 using the Immersed Boundary Method. For the purpose of observing the phenomen...
The present study numerically investigates two-dimensional
laminar fluid flow and heat transfer past a circular cylinder under a forced oscillating normal to the free-stream flow at a fixed Reynolds number equal to 185 using the Immersed Boundary Method. For the purpose of observing the phenomenon of vortex shedding resonance or lock-in, numerical simulations are performed for different
oscillating amplitude( / e A D) in the range of 0.2 / 0.5 e A D ≤ ≤ and a fixed Prandtl number of 0.7(air) in the range of 0.8 1.2 r f ≤ ≤ , where r f is the ratio of excitation frequency to natural shedding frequency. The present study reports the detailed information of phase-averaged flow and thermal quantities at the extreme high position for the different oscillating amplitudes. The phase-averaged flow and
thermal fields of the cylinder oscillating with the various frequency ratios show the synchronized wake pattern in the lock-in region and vortex switching phenomenon at the frequency ratio higher than a critical frequency ratio.
Numerical simulations are conducted for Reynolds number of 100 and Prandtl number of 0.7(air) past two cylinders rotating in the antiphase direction. This study aims at investigating the effect of the rotation on the characteristics of flow and heat transfer over the two cylinders, when the gap, * g between two cylinder ranges from 0 to 3.0. The rotational speeds are in the range of 0 2 α ≤ ≤ , where αis the maximum velocity on the cylinder surface normalized by a freestream velocity. We consider two different rotational directions regarding to the upper and lower cylinders. One is the clockwise and counter-clockwise direction (CASE I) and another is the counter-clockwise and clockwise direction (CASE II) for the upper and lower cylinders, respectively. At
α =0(without rotation), the flow and thermal fields past the two
cylinders has the anti-phase synchronized, in-phase synchronized, flip-flopping, single bluff-body wake patterns at * g =3.0, 1.5, 0.7 and 0.2, respectively. For CASE I, these wake patterns corresponding to * g have been modified with increasing α . When α reaches the critical value ( , C t α ) depending on the * g , the flow and thermal fields
become stabilized. However, for CASE II, , C t α could not be obtained in the range of α considered in this study. For both CASEs, the dependency of the wake patterns, hydrodynamic forces, vorticity, pressure coefficient, stagnation points and Strouhal number as flow characteristics and also Nusselt number as heat transfer
characteristics on the α and * g have been examined in detail.
The present study numerically investigates two-dimensional
laminar fluid flow and heat transfer past a circular cylinder under a forced oscillating normal to the free-stream flow at a fixed Reynolds number equal to 185 using the Immersed Boundary Method. For the purpose of observing the phenomenon of vortex shedding resonance or lock-in, numerical simulations are performed for different
oscillating amplitude( / e A D) in the range of 0.2 / 0.5 e A D ≤ ≤ and a fixed Prandtl number of 0.7(air) in the range of 0.8 1.2 r f ≤ ≤ , where r f is the ratio of excitation frequency to natural shedding frequency. The present study reports the detailed information of phase-averaged flow and thermal quantities at the extreme high position for the different oscillating amplitudes. The phase-averaged flow and
thermal fields of the cylinder oscillating with the various frequency ratios show the synchronized wake pattern in the lock-in region and vortex switching phenomenon at the frequency ratio higher than a critical frequency ratio.
Numerical simulations are conducted for Reynolds number of 100 and Prandtl number of 0.7(air) past two cylinders rotating in the antiphase direction. This study aims at investigating the effect of the rotation on the characteristics of flow and heat transfer over the two cylinders, when the gap, * g between two cylinder ranges from 0 to 3.0. The rotational speeds are in the range of 0 2 α ≤ ≤ , where αis the maximum velocity on the cylinder surface normalized by a freestream velocity. We consider two different rotational directions regarding to the upper and lower cylinders. One is the clockwise and counter-clockwise direction (CASE I) and another is the counter-clockwise and clockwise direction (CASE II) for the upper and lower cylinders, respectively. At
α =0(without rotation), the flow and thermal fields past the two
cylinders has the anti-phase synchronized, in-phase synchronized, flip-flopping, single bluff-body wake patterns at * g =3.0, 1.5, 0.7 and 0.2, respectively. For CASE I, these wake patterns corresponding to * g have been modified with increasing α . When α reaches the critical value ( , C t α ) depending on the * g , the flow and thermal fields
become stabilized. However, for CASE II, , C t α could not be obtained in the range of α considered in this study. For both CASEs, the dependency of the wake patterns, hydrodynamic forces, vorticity, pressure coefficient, stagnation points and Strouhal number as flow characteristics and also Nusselt number as heat transfer
characteristics on the α and * g have been examined in detail.
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