Sharen J. Cummins

How arterial pressures affect the consideration of internal carotid artery angle as a risk factor for carotid artherosclerotic disease

Patient–specific geometric factors together with traditional risk factors may aid the early identification of patients at high risk of developing carotid artery disease requiring surgical intervention. Recent studies have linked aspects of carotid geometry to the pathogenesis of internal carotid artery (ICA) stenosis. Abnormal wall shear stress (WSS) is found for large ICA angles. Low WSS is believed to correspond to plaque formation whereas high WSS may result in plaque rupture and clotting. Here, the meshless method, smoothed particle hydrodynamics, is used to simulate Newtonian flow through a clinical, rigid walled, carotid bifurcation. The resulting flow field and WSS are reported for a range of different ICA angles. Varying the angle without changing boundary pressure conditions produces minimal change in flow and WSS. Greater ICA downstream pressures appear important for maintaining well–behaved flow through the bifurcation by suppressing flow separation downstream of the stenosis resulting in more uniform wall stress.

Aiming for Modeling-Assisted Tailored Designs for Additive Manufacturing

It is well recognized that there are gaps in knowledge on the strongly intertwined process–microstructure–property–performance relationships inherent in the metallic additive manufacturing processes. Computational modeling can assist with filling in some of these gaps by increasing in-depth understanding of these relationships and highlighting cause-and-effect. Additionally, it can capture the knowledge of materials scientists and engineers and apply established physics-based rules to simulate the processes and thus predict the final outcomes. Modeling can also help optimize processes. Some even predict that future generations of additive manufacturing machines will employ ‘model-assisted feed forward algorithms’ that would leapfrog feedback control methods. In the current article the authors describe the several computational efforts sponsored by CSIRO’s ‘Lab 22—Australia’s Centre for Additive Innovation’ aimed at modeling-assisted tailored design. The models in development, e.g. microstructure prediction (both fundamental and empirical), powder bed raking, and residual stress predictions, are described in some detail, and representative results are presented.

The effect of pressure solution in SPH simulations of sloshing flow

In modelling incompressible flows using the Smoothed Particle Hydrodynamics method (SPH), an equation of state with a large sound speed is typically used. This weakly compressible approach (WCSPH), results in a stiff set of equations with a noisy pressure field and stability issues at high Reynolds number. As a remedy, an incompressible SPH technique was introduced [1] (ISPH), which uses a pressure projection technique to model incompressibility. In this paper, the incompressible and weakly compressible forms of the SPH method are employed to study sloshing flow. Both methods are compared with experimental data. The results show the incompressible SPH method provides more accurate pressure fields and free-surface profiles when compared to experiment.Copyright