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This study is concerned with understanding and improvement of mass flow rate measurement uncertainty and errors encountered at low flow rates and start-up in commercially available flow rate measurement devices, such as orifice flow meters. The flow through a typical cylindrical flange-tapped orifice flow meter is modeled computationally so the actual mass flow rate is known a-priori. Empirical predictions from the reading of “virtual” pressure sensors are compared with the actual flow rate and the measurement errors are quantified and analyzed. Commercial code ANSYS-Fluent is compared in this study to the in-house high-fidelity spectral-element solver Nek5000, so that conclusions about the applicability of a commercial code to the calculations of measurement uncertainty in the orifice flow meters can be made.

Fluid structure interaction (FSI) describes a problem when a solid structure deforms or oscillates by the influence of the fluid flow, and thus a two-way interaction occur, such as in wind turbines, airfoils, parachutes, biological systems, including aneurysms, etc. One of the major challenges in the numerical simulation of this problem is the computational cost, and most of the current solvers are using an implicit method for fluid, with Newton-Raphson method being the most popular. However, an explicit method is relatively cheap. In this paper, explicit method with sub-iterations is compared with a Newton-Raphson method through an FSI benchmark case. We concentrate on comparison of accuracy as well as the computational performance of the two methods.