MODELLING LAMINAR NON-NEWTONIAN FLUID FLOW BETWEEN PARALLEL PLATES BY A DEVELOPED CFD CODE


Önen M. C. , Parlak Z.

8. ULUSLARARASI MÜHENDİSLİK MİMARLIK VE TASARIM KONGRESİ, İstanbul, Turkey, 6 - 07 December 2021, vol.8, pp.522-532

  • Publication Type: Conference Paper / Full Text
  • Volume: 8
  • City: İstanbul
  • Country: Turkey
  • Page Numbers: pp.522-532

Abstract

The term rheology has a great impact on the velocity profile of a fluid flow by linking the shear stresses and shear rates in a control volume. Despite this relationship is proportional in many fluids in the industry called Newtonian type, most of the fluids we interact with within our daily lives have non-Newtonian characteristics showing non-proportional relation. For instance, human blood, petrol, some medical mixtures, paint, toothpaste, shampoo, etc. Such fluids having non-Newtonian characteristics means that their viscosity is a variable especially at the interactions with fluid-solid interfaces, such as wall boundaries. In the present study, the modeled non-Newtonian fluid fits the Herschel Bulkley model that includes the yield stress and shear thinning behavior. Therefore, a fluid having yield stress causes a region with no shear rate called plug flow in the control volume where the local shear stresses are below the yield stress. The CFD solution of a non-Newtonian fluid requires special treatment on both the Momentum equation and the rheology expressions. This work covers a laminar flow analysis of a non-Newtonian fluid realized by a developed in-house CFD code. As a result, the work obtained the velocity profile and pressure distribution along the 2D parallel plate control volume through the inclusion of the Herschel Bulkley rheology model to the momentum equations. Significant positive compatibility was observed between the velocity and pressure distributions obtained with different discretization schemes. This study is derived from the works of the author’s Master thesis.