Numerical simulation of flow in trapezoidal labyrinth-channels of drip irrigation

Abstract

The clogging of emitters has been considered as one of the most troublesome problems inhibiting the extension of drip irrigation. This paper investigates the flow field of water and behaviour of suspended particles in the trapezoidal labyrinth-channel. Computational Fluid Dynamics methods has been executed on liquid-solid two-phase flow in labyrinth-channel emitters. RNG k-e turbulence model was used to evaluate four types of emitters that have the same characteristics and differ in the elbow width S. This study has shown that as the value of S increases, the maximum velocity in the labyrinth-channel decreases and the number of vortices increases. However, emitter with a high S value are more subtle to clogging. In addition, it was also observed that smaller diameter particles behave best when they pass through the channel and follow the streamline flow. As the particle diameters become larger, the particles tend to leave the mean stream and enter the vortex zones under the force of inertia. So, more suspended particles trapped in the vortex area , more the chances of emitter clogging increase. All of these furthermore confirm that vortex and low speed regions were the main causes leading to emitter clogging.

Numerical simulation of clogging of two types of emitters with similar properties

“…Several investigations have been based on the numerical study of the flow behavior in emitters (Wei et al, 2009). They found that, at the emitter level, the areas where particles can be deposited are the low flow velocity areas, the corners, and the vortex areas (Ouarriche et al, 2021; Zhang et al, 2007).…”

Sensibilidade à obstrução por partículas sólidas de emissores contínuos integrados à fita gotejadora

“…Como descrito anteriormente, a Figura 52C possibilita a visualização da região de estagnação, onde as partículas foram encontradas e, provavelmente, podem ter iniciado a sedimentação ao longo do labirinto da maioria dos emissores do Modelo 2 avaliado para cima. Esse cenário possivelmente tem relação com a força de arraste e a força inercial ocorrendo nas partículas dentro do labirinto, sendo que a força inercial é proporcional ao diâmetro da partícula e a força de arraste segue uma relação com o quadrado do tamanho da partícula, ou seja, à medida que os diâmetros das partículas se tornam maiores essas tendem a sair da zona de fluxo principal e entrar nas zonas de vórtices (OUARRICHE et al, 2021).…”