In fact, for a fluid, there are two different moving states. One is called laminar, which is smooth and stable, another one is known as turbulent, which is chaotic and unstable. Under the situation of this saying, a laminar flow bears the boat and turbulent swallows it up.

Pipe flow is a common fluid dynamics application in transportation engineering, for instance, South–North Water Transfer Project and West–East Gas Pipeline in China. We require the fluid to be stable and smooth such that the water and the gas can be consistently transferred to avoid any safety issues due to the high turbulent kinetic energy. But is there any possibility to control it? Can we decide the fluid in the pipe to be laminar or turbulent?

With this question in my mind, I start this research of “Onset of Turbulence in a Channel Flow” with Dr. Christian Thomas.

The state of the flow can be determined by the dimensionless Reynolds number denoted by the product of the velocity of the fluid and the diameter of the pipe divided by the kinematic viscosity of the fluid. In this quantity, the kinematic viscosity is the property of the fluid, which means it is a constant. In our investigation of two dimensional Poiseuille flow, the velocity of the fluid and the diameter of the pipe could be controlled where the velocity is related with pressure applied and the diameter is pre-constructed/planned. The Reynolds number of a certain channel flow is under human control. In a different perspective, we can replicate an existing channel flow by an easy-built flow with the same Reynolds number. Doesn’t it sound exciting?

But how do we quantitively manage the movement of the fluid?  What is the critical condition? To find out the detail of the formulation and the numerical result, it is my pleasure to show you these things in my report.

Yixin Kang
Macquarie University

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