CFD modeling for moving jet penetrating cohesive soil

Master thesis (2019)

Authors

Contributors

G.H. Keetels Offshore and Dredging Engineering - Mechanical, Maritime and Materials Engineering (mentor)

A. Jarquin Laguna Offshore and Dredging Engineering - Mechanical, Maritime and Materials Engineering (graduation committee member)

A.H. van Zuijlen Aerodynamics - Aerospace Engineering (graduation committee member)

Faculty

Mechanical Engineering, Mechanical Engineering

CFD Cohesive soil Drift-flux model Dynamic mesh Moving jet

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Published Date

26-09-2019

Language

English

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Faculty

Mechanical Engineering

Abstract

In dredging
operation, the high-pressure water jet is widely used for the excavation of
soil. To study the jetting process and optimize the dredging devices, the
moving vertical water jet penetrating cohesive soil experiments were carried
out by Nobel (2013). However, in terms of the design optimization for the
dredging devices, it is not easy to change the jet scale and soil properties
during the experiment due to time and economic constraints. Some detailed
physics during the jetting process, e.g. pressure on the soil surface and shear
plane inside the soil during jetting, were also not monitored during the
experiment. Therefore, numerical simulation is chosen to optimize the design of
dredging devices and study the physics of the jetting process. A CFD (computational
fluid dynamics) numerical model is built to simulate the moving jet penetrating
cohesive soil. The soil is modeled as a Bingham plastic. The sediment transport
is modeled by using drift-flux model. The moving jet modeling is achieved by
using dynamic mesh algorithms AMI (arbitrary mesh interface) and A/R (cell
layer addition removal). The CFD numerical model has been validated with the
experiment of Nobel. After the validation, an analysis of the jetting process
based on this CFD model is accomplished proving that the CFD model can reveal
the details of the soil failure process during jetting. This thesis work
reveals that it is possible to describe the hydraulic excavation of cohesive
soil with reasonable accuracy using CFD numerical model. The CFD model can also
reveal the details of the soil failure process that could not be retrieved from
the experiment. Since the model is generic, it can be applied for a jet bar
with multiple nozzles. This is helpful to improve the design of dredging equipment,
optimize the operational settings and estimate the production.

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