In the engineering world, studying non-Newtonian fluids in corrugated channels is an intriguing way to investigate complicated flow processes. Researchers get valuable insights into industrial processes and biomedical engineering by studying non-Newtonian fluids, which have a viscosity that changes with shear rate. These studies improve our understanding of non-Newtonian fluid dynamics and enable the optimization and design of novel systems and processes.

Based on the reference paper entitled “Experimental characterization of Newtonian and non-Newtonian fluid flows in corrugated channels”, we conducted a CFD simulation to dive into the non-newtonian fluids world, specifically in a corrugated channel shown below.

• Reference [1]: Bereiziat, D., and R. Devienne. “Experimental characterization of Newtonian and non-Newtonian fluid flows in corrugated channels.” International journal of engineering science11 (1999): 1461-1479.

Figure 1: Details of the tested geometry – Corrugated Channel

Simulation Process

The sinusoidal walls of the corrugated channel are designed using construction points in Design Modeler. It is important to know that the shear stress applied is influential and requires a fine grid near the walls. So, a structured grid is generated.

The flow regime remains laminar through its movement in a corrugated channel. According to the definition of a non-newtonian fluid, the viscosity is totally shear rate dependent, so the Herschel-bulkly viscosity method is employed to define a relation between viscosity and strain rate. The channel walls are also warmer than the flow inside, resulting in heat transfer.

Figure 2: structured grid over sinusoidal channel

Post-processing

The computational fluid dynamics (CFD) modeling shows interesting non-Newtonian fluid behavior in the wavy channel. The velocity curves show an interesting phenomenon: the fluid moves at its fastest (0.22 m/s) along the centerline, but it also forms clear recirculation zones in the depressions of the corrugations. As you can see, this flow pattern is very interesting because it shows how non-Newtonian fluids behave, where the viscosity drops in areas with high shear rates close to the walls. The sinusoidal shape causes the flow to speed up and slow down on a regular basis. This creates a self-sustaining mixing process that improves heat transfer, as shown by the temperature differences between 288K and 296K.

The thermal contours show how fluid dynamics and heat transfer processes work together in a complicated way. The wavy shape makes thermal boundary layers that break up and then come back together again and again. This makes mixing and heat movement better than in straight channels. Near the walls, where the fluid is moving the slowest, there are clear layers of temperature, but the temps stay pretty even in the core flow. This thermal behavior, along with the non-Newtonian rheology, creates a unique flow regime where changes in viscosity caused by both shear rate and temperature effects control the transport phenomena. This makes it especially useful for use in biomedical fluid transport systems and the processing of polymers.

Figure 3: Velocity streams & temperature field in Non-newtonian Fluid in Corrugated Channel CFD Simulation