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Projecte llegit

Títol: Design of the test cell of an orbital experiment

Estudiants que han llegit aquest projecte:

Director/a: GONZÁLEZ CINCA, RICARD

Departament: FIS

Títol: Design of the test cell of an orbital experiment

Data inici oferta: 08-05-2025     Data finalització oferta: 08-01-2026


Estudis d'assignació del projecte:
    GR ENG SIST AEROESP
Tipus: Individual
 
Lloc de realització: EETAC
 
Segon director/a (UPC): LEAL ABADI, LUCAS
 
Paraules clau:
COMSOL CFD Microgravity Liquid Simulation
 
Descripció del contingut i pla d'activitats:
.
 
Overview (resum en anglès):
Mixing liquids is a fundamental operation in fluidic systems; however, under microgravity conditions, the absence of buoyancy-driven convection significantly alters the underlying transport mechanisms. In such environments, conventional mixing processes that rely on density differences or gravitational forces become ineffective, and fluid behavior is instead dominated by diffusion, interfacial dynamics, and flow induced by external actuation. Understanding and controlling liquid mixing in microgravity is therefore a critical challenge for fluid management systems intended for space-based experiments and platforms.
This Final Degree Thesis investigates the mixing of two miscible liquids initially contained within a closed chamber operating under microgravity conditions using COMSOL's CFD module. At the start of the process, both liquids coexist in the chamber, forming an interface between them. The objective of the thesis is to understand how mixing progresses from this initial configuration and to identify methods to accelerate homogenization in the absence of gravitational forces.
In the passive case, mixing occurs mainly through molecular diffusion across the liquid-liquid interface. Since the flow regime is laminar and no buoyancy-induced motion is present, concentration gradients persist over long timescales, and the characteristic mixing time is dictated by the diffusion coefficient and the characteristic length of the chamber. The geometry of the chamber and the initial spatial distribution of the liquids therefore play a critical role in determining the efficiency of passive mixing and the formation of unmixed or weakly mixed regions.
To overcome the limitations of diffusion-dominated mixing, the system incorporates an active mixing mechanism based on a piezoelectric transducer (PZT). The PZT is used to introduce controlled mechanical vibrations into the chamber, generating oscillatory flows and localized shear within the liquid volume. The use of piezoelectric actuation is particularly well suited for microgravity applications, as it provides precise control over the amplitude and frequency of the induced motion while requiring minimal power and mechanical complexity.
This thesis combines fluid dynamics theory and numerical modeling to analyze both passive and actively enhanced mixing within the chamber. The evolution of concentration fields, velocity distributions, and mixing efficiency is studied to assess the effectiveness of the PZT-based actuation compared to purely diffusive mixing. The outcome of this work aims to support the design of a payload regarding the development of embryos in space, for a project involving the Space Exploration Laboratory of BarcelonaTech, the Spanish Space Agency and the Plachta Lab at the University of Pennsylvania among others.

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