CHNS example : bubble detachment in a shear flow #1334
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blaisb
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Nov 4, 2024
.../multiphysics/bubble-detachment-shear-flow/parametric_sweep/bubble-detachment-shear-flow.prm
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| #!/bin/bash | |||
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| - Solver: ``lethe-fluid`` (Q1-Q1) | ||
| - Two phase flow handled by the Cahn-Hilliard-Navier-Stokes (CHNS) approach | ||
| - Dimensionality of the length |
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| - Dimensionality of the length | |
| - Dimensionality of the length |
I understand what you mean here and I don't know how to word that better, but I still think the wording here could be improved
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I suggest "Changing the unit of length of the problem using the dimensionality option"
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| Bubble detachment in shear flow plays a key role in multiphase flows, where shear forces influence the separation of air bubbles from surfaces. This process is important in industries like petroleum engineering, where bubble behavior affects oil extraction, and chemical processing, where it impacts mixing and mass transfer. In this example, we simulate an air bubble in water under shear flow, highlighting how shear forces drive detachment from the interface. | ||
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| The problem consists of a rectangular box of length :math:`L = 12 \ \text{mm}`, height :math:`H = 5 \ \text{mm}` and thickness :math:`l = 5 \ \text{mm}`. The liquid phase flows from left to right following a Couette profile, that is determined with a given **shear rate**. At the bottom wall is a circular air inlet of radius :math:`R_0 = 0.5 \ \text{mm}`. Air is injected from this inlet following a Poiseuille profile. As the time passes, the bubble, which is initialized as a semi-sphere of radius :math:`R_0`, grows, until the shear force from the surrounding liquid and the buoyancy force detach it. |
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Why is shear-rate in italic like that?
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I want to emphasize that the Couette profile is determined from the shear rate, since we're only using the shear rate in what follows
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| The quantity of interest of this problem is the detachment time :math:`t_\text{det}`. It is defined as the last time where the number of closed contour of the phase order field is equal to 1. From this, we derive the detachment volume :math:`V_\text{det}`, which is the bubble volume at :math:`t_\text{det}`. We perform numerous simulations by changing the shear rate and compute the detachment times and volumes using the python scripts provided. Those results are then compared to the results from Mirsandi *et al.* [#mirsandi2020]_ | ||
| Below, all the parameters are set for a simulation whose shear rate :math:`S = 500 \ \text{s}^{-1}`. Detailed instructions on how to generate the parameters files automatically are given in the "Running the Simulation" section of this example. |
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maybe italic for running the simulation instead of just quotes.
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I agree that quoted is not great, but maybe bold would be better?
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| .. Note:: When using the dimensionality parameters, the problem and the physical properties are rescaled using the new units specified by the user. This means that physical properties can be given their value in SI units and will automatically be rescaled. The resulting fields (velocity and pressure for instance) will also be rescaled accordingly. One exception to this is the source terms and the initial conditions, which need to be specified in rescaled units. | ||
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I guess also boundary conditions right?
It only rescales the unit for the physical properties in the end.
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I clarified this part
doc/source/examples/multiphysics/bubble-detachment-shear-flow/bubble-detachment-shear-flow.rst
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Once the capillary rise example is merged into master, the branch will be rebased and pass the tests (related to the architecture of the documentation)
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| - Solver: ``lethe-fluid`` (Q1-Q1) | ||
| - Two phase flow handled by the Cahn-Hilliard-Navier-Stokes (CHNS) approach | ||
| - Dimensionality of the length |
There was a problem hiding this comment.
I suggest "Changing the unit of length of the problem using the dimensionality option"
|
|
||
| Bubble detachment in shear flow plays a key role in multiphase flows, where shear forces influence the separation of air bubbles from surfaces. This process is important in industries like petroleum engineering, where bubble behavior affects oil extraction, and chemical processing, where it impacts mixing and mass transfer. In this example, we simulate an air bubble in water under shear flow, highlighting how shear forces drive detachment from the interface. | ||
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|
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| The problem consists of a rectangular box of length :math:`L = 12 \ \text{mm}`, height :math:`H = 5 \ \text{mm}` and thickness :math:`l = 5 \ \text{mm}`. The liquid phase flows from left to right following a Couette profile, that is determined with a given **shear rate**. At the bottom wall is a circular air inlet of radius :math:`R_0 = 0.5 \ \text{mm}`. Air is injected from this inlet following a Poiseuille profile. As the time passes, the bubble, which is initialized as a semi-sphere of radius :math:`R_0`, grows, until the shear force from the surrounding liquid and the buoyancy force detach it. |
There was a problem hiding this comment.
I want to emphasize that the Couette profile is determined from the shear rate, since we're only using the shear rate in what follows
| +-------------------------------------------------------------------------------------------------------------------+ | ||
|
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| The quantity of interest of this problem is the detachment time :math:`t_\text{det}`. It is defined as the last time where the number of closed contour of the phase order field is equal to 1. From this, we derive the detachment volume :math:`V_\text{det}`, which is the bubble volume at :math:`t_\text{det}`. We perform numerous simulations by changing the shear rate and compute the detachment times and volumes using the python scripts provided. Those results are then compared to the results from Mirsandi *et al.* [#mirsandi2020]_ | ||
| Below, all the parameters are set for a simulation whose shear rate :math:`S = 500 \ \text{s}^{-1}`. Detailed instructions on how to generate the parameters files automatically are given in the "Running the Simulation" section of this example. |
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I agree that quoted is not great, but maybe bold would be better?
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| .. Note:: When using the dimensionality parameters, the problem and the physical properties are rescaled using the new units specified by the user. This means that physical properties can be given their value in SI units and will automatically be rescaled. The resulting fields (velocity and pressure for instance) will also be rescaled accordingly. One exception to this is the source terms and the initial conditions, which need to be specified in rescaled units. | ||
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I clarified this part
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| | | | ||
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| Below are the plots of the contour of the bubble in the plane :math:`z = 0` when detachment occurs for different values of the shear rate. |
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Do you want to add one of your video?
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Yes! I still need to make them prettier with @AmishgaAlphonius though
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I am good with this @PierreLaurentinCS . So if this is ready for merge, just tell me and I will merge it.
…un the simulations
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Description This is the second example of the Cahn-Hilliard-Navier-Stokes solver. The solver is used to simulate the detachment of bubbles in a shear flow in three dimensions. The quantities of interest (detachment time and volume) are compared to values from the literature. An excellent agreement is observed, which confirms that the CHNS solver is able to describe complex interface physics, involving break-up and jet formation. All the necessary files to run the parametric sweep are included (only on the shear rate) and python scripts are provided to reproduce the figures if needed (see the previous PR : #1307).
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Description
This is the second example of the Cahn-Hilliard-Navier-Stokes solver. The solver is used to simulate the detachment of bubbles in a shear flow in three dimensions. The quantities of interest (detachment time and volume) are compared to values from the literature. An excellent agreement is observed, which confirms that the CHNS solver is able to describe complex interface physics, involving break-up and jet formation.
All the necessary files to run the parametric sweep are included (only on the shear rate) and python scripts are provided to reproduce the figures if needed (see the previous PR : #1307).
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