Paper Number
IN33 

Session
Flow Induced Instabilities and Non-Newtonian Fluids

Title
Shear-induced sedimentation of a sphere in yield stress fluids: A computational study

Presentation Date and Time
October 23, 2019 (Wednesday) 11:30

Track / Room
Track 4 / Room 305B

Authors (Click on name to view author profile)

  1. Sarabian, Mohammad (Ohio University, Mechanical Engineering)
  2. Rosti, Marco (KTH Mechanics)
  3. Brandt, Luca (KTH Mechanics)
  4. Hormozi, Sarah (Ohio University)

Author and Affiliation Lines (in printed abstract book)
Mohammad Sarabian1, Marco Rosti2, Luca Brandt2, and Sarah Hormozi1
1Mechanical Engineering, Ohio University, Athens, OH 45701; 2KTH Mechanics, Stockholm, Sweden

Speaker / Presenter 
Sarabian, Mohammad

Text of Abstract
We numerically investigate the sedimentation of a single sphere subjected to a simple cross shear flow in a complex fluid. The fluid has viscous, elastic and plastic behavior and is well known as elastoviscoplastic (EVP) fluid. Sacramento's constitutive equation is employed to model the EVP fluid (Saramito (2009) [1]). We have recently developed a there dimensional numerical solver to study suspensions of rigid and soft particles and droplets in EVP fluids (Izbassarov et al. (2018) [2]). The solid particle is represented by an immersed boundary method (IBM) with a computationally efficient multi-direct forcing scheme. The main objective of this work is to understand how a cross shear flow affects the drag force on a sphere. We calculate the magnitude of different drag components (viscous drag, form drag, and elastoplastic drag) on the particle and discuss the primary cause of drag enhancement or reduction on the settling of a sphere when a cross shear flow is imposed. We show the dependency of the drag coefficient on plastic and elastic properties of the suspending fluid as well as the nonlinear coupling of the settling flow and the cross shear flow [1] Saramito, P. (2009). A new elastoviscoplastic model based on the Herschel–Bulkley viscoplastic model. Journal of Non-Newtonian Fluid Mechanics, 158(1-3), 154-161. [2] Izbassarov, D., Rosti, M. E., Ardekani, M. N., Sarabian, M., Hormozi, S., Brandt, L., & Tammisola, O. (2018). Computational modeling of multiphase viscoelastic and elastoviscoplastic flows. International Journal for Numerical Methods in Fluids, 88(12), 521-543.