Investigation of blood flow rheology using second-grade viscoelastic model (Phan-Thien–Tanner) within carotid artery

Purpose: Hemodynamic factors, such as Wall Shear Stress (WSS), play a substantial role in arterial diseases. In the larger arteries, such as the carotid artery, interaction between the vessel wall and blood flow affects the distribution of hemodynamic factors. The fluid is considered to be non-Newtonian, whose flow is governed by the equation of a second-grade viscoelastic fluid and the effects of viscoelastic on blood flow in carotid artery is investigated. Methods: Pulsatile flow studies were carried out in a 3D model of carotid artery. The governing equations were solved using finite volume C++ based on open source code, OpenFOAM. To describe blood flow, conservation of mass and momentum, a constitutive relation of simplified Phan-Thien–Tanner (sPTT), and appropriate relations were used to explain shear thinning behavior. Results: The first recirculation was observed at t = 0.2 s, in deceleration phase. In the acceleration phase from t = 0.3 s to t = 0.5 s, vortex and recirculation sizes in bulb regions in both ECA and ICA gradually increased. As is observed in the line graphs based on extracted data from ICA, at t = 0.2 s, τyy is the maximum amount of wall shear stress and τxy the minimum one. The maximum shear stress occurred in the inner side of the main branch (inner side of ICA and ECA) because the velocity of blood flow in the inner side of the bulb region was maximum due to the created recirculation zone in the opposite side in this area. Conclusions: The rheology of blood flow and shear stress in various important parts (the area that are in higher rates of WSS such as bifurcation region and the regions after bulb areas in both branches, Line1–4 in Fig. 7) were also analyzed. The investigation of velocity stream line, velocity profile and shear stress in various sections of carotid artery showed that the maximum shear stress occurred in acceleration phase and in the bifurcation region between ECA and ICA which is due to velocity gradients and changes in thinning behavior of blood and increasing strain rate in Newtonian stress part

Value based pricing of distribution generations active power in distribution networks

With widespread installation of distribution generations (DG) mainly in distribution networks, a fairly incentive scheme is required to better meet the investment and innovation challenge and to drive the innovation needed to deliver a sustainable energy network with value for money to existing and future consumers. This study proposes a new method to determine DG energy price based on its impact on active loss reduction. This method calculates the actual value of each DG in the active loss reduction and according to this value, determines DG energy price, which is named value based pricing. The proposed approach is applied to a market model with two different agents, namely considered as the distribution company (DisCo) and the owner of DG. In this model, the DisCo is considered as the sole owner and operator of a distribution network and can purchase energy from the wholesale electricity market and/or from DG units owned by independent producers. To illustrate the advantages of the proposed method compared with the local marginal pricing(, both methods are implemented in 33-bus distribution network.</p