LisMath Seminar 

26/06/2018, 14:00 — 14:30 — Room 6.2.33, Faculty of Sciences of the Universidade de Lisboa
Hillal M. Elshehabey, LisMath, Instituto Superior Técnico

Mathematical Modelling and Numerical Simulation of an Anaerobic Digester

Anaerobic digestion is a bacterial process, carried out in the absence of oxygen, used to convert the organic fraction of large volumes of slurries and sludge into biogas and a digested product. The objective of this work is to perform a numerical modeling of the fluid dynamics process inside an anaerobic digestion tank and numerical simulations of the model, which might indicate properly sized extra piping and pumping systems, in order to minimize the deposition of inert materials. This research is being developed within a consulting project for Valorlis - Valorização e Tratamento de Resíduos Sólidos, SA.

In this seminar, we begin by presenting the mathematical model which describes the behavior of the pseudo-plastic fluid in the tank, where parameters such as temperature and total solids content are compatible with several experimental cases reported in the literature and have been validated by Valorlis. The influence of such parameters in the fluid behavior will be discussed in simpler, classical geometries.

Following [1], we propose alternative conditions for outflow. The benefits of using the directional do-nothing boundary condition comparing with the classical one [1] will be presented for the proposed non-Newtonian model and for some benchmark problems, including a comparison with the Newtonian model.

Bibliography:

[1] M. Braack and P. B. Mucha, Directional do-nothing condition for the Navier-Stokes equations, Journal of Computational Mathematics, 32, No.5 (2014), 507-521.