**Numerical study of stress tensors in Poiseuille flow of suspensions**

A Chatterjee and DR Heine, PHYSICAL REVIEW E, 82, 021401 (2010).

DOI: 10.1103/PhysRevE.82.021401

In this paper, the flow of dense suspensions of monodisperse spheres in
wall-bounded channels is studied using a mesoscopic numerical model
based on the dissipative particle dynamics (DPD) technique. Experimental
observations **for instance, L. Isa et al., Phys. Rev. Lett. 98, 198305
(2007)** have confirmed that understanding the relevant physics of this
problem requires probing at the mesoscopic level to account for the
particle scale behavior. The DPD-based approach presented here enables
us to explore various aspects of suspension flow at the particle scale.
The yielding behavior of the suspensions is studied using macroscopic
stress components calculated from the particle level. The relationship
between various normal and shear stress components at the yielding plane
is presented and discussed. It is seen that in dense suspensions,
yielding is characterized by a strong dependence on all the stress
components: tau(xx), tau(xy), and tau(yy). It is also seen that
different stress components have different length-scale dependencies.
While the normal stress in the flow direction, tau(xx), depends on
macroscopic parameters such as the driving force, tau(yy), the normal
stress transverse to the flow, depends on particle level parameters and
is independent of the driving force. Wall topologies with characteristic
dimensions on the order of the suspension particle size have a strong
effect on the flow characteristics and the stress components.

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