Numerical Modelling and Validation of Shear thinning flows in a lab-scale digester

Sathyanarayanan Nagasundaram, Artur Krzysztof Pozarlik, Hossein Norouzi Firouz, Gerrit Brem

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Anaerobic digestion is a process of biochemical conversion of bio-waste into a fuel-gas mixture (methane+carbon dioxide) by bacteria, in the absence of oxygen. The process is carried out in a tank which is referred to as a digester and the efficiency of the biochemical waste conversion process is dependent on several factors, with mixing being one of the key factors.

A typical digester measures up to 20 meters in height and diameter and if the role of mixing in the intensification of biogas production in a full scale digester is to be studied, the numerical models first need to be verified. In this paper, the available CFD numerical models are first applied to model a shear-thinning flow in a lab scale digester and the flow variable data from computations are compared against available PIV measurements for the same digester. The flow variables considered in the validation are the turbulent kinetic energy and the mean velocities. The RNG k-epsilon model is found out to be the most suited turbulence model to simulate shear-thinning and the Multiple Reference Frame (MRF) approach was found to be fairly accurate and computationally economical in predicting flow trends.

KEYWORDS: Anaerobic digestion, CFD, Numerical modelling, Shear-Thinning flows
Original languageEnglish
Publication statusSubmitted - 15 May 2019
Event16e Anaerobic Digestion Conference 2019 - TU Delft, Delft, Netherlands
Duration: 23 Jun 201927 Jun 2019
Conference number: 16


Conference16e Anaerobic Digestion Conference 2019
Abbreviated titleAD 2019
Internet address


  • Anaerobic digestion
  • Shear thinning flows
  • Numerical modelling
  • CFD


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