A Predictive Model for Fiber Orientation Dynamics in Viscoplastic Flows from Experimental PIV and PTV on Carbopol as UHPC Analogue
| dc.contributor.author | Wolff Casanova, Lukas | |
| dc.date.accessioned | 2026-10-21T14:40:34Z | |
| dc.date.available | 21-10-26 11:40 | |
| dc.date.issued | 2026-08 | |
| dc.description | Tesis para optar al grado académico de Magíster en Ciencias de la Ingeniería | |
| dc.description.abstract | Modern reinforced concrete structures are subject to increasing demands in terms of service life, performance and efficiency. In addition, the high and growing demand for concrete has driven the construction industry to seek advanced cementitious materials. Ultra High Performance Concrete (UHPC) is a material that, through the optimization of the packing of its matrix, the use of superplasticizing admixtures and the addition of steel fibers, achieves not only a high mechanical performance, above 150 MPa in compression and on the order of 15 MPa in tension, but also a service life exceeding 200 years. The literature indicates that fibers play a fundamental role, where the alignment and dispersion of the fibers with respect to the loading direction are the governing factors of the mechanical response. Both parameters arise from the casting process and depend directly on the rheology of the mixture and on the fiber content. Particle Image Velocimetry (PIV) was implemented on Carbopol, a transparent non-Newtonian viscoplastic fluid used to replicate the rheological properties of UHPC, in order to study the Eulerian behavior of the flow. Additionally, the Particle Tracking Velocimetry (PTV) methodology was implemented to study the Lagrangian behavior of the fibers. The experimental campaign employed Carbopol at concentrations of 0.2% and 0.5%, and four fiber contents: a control without fibers and dosages equivalent to 0.72, 1.48 and 2.92 times the dilute limit. The PIV and PTV measurements determined that the dominant factors are the cross section geometry and the rheology of the mixture. However, it was observed that at higher fiber concentrations the fibers experience a higher angular velocity, while the vorticity of the flow remains practically unaltered. Furthermore, the final alignment of the fibers decreases with concentration. All of these effects are predicted by the Advani-Tucker model for Newtonian flows. On this basis, this thesis proposes a reduction of the Advani-Tucker model to an exponential approach-to-equilibrium law with two parameters, the attainable alignment η1,max and the characteristic strain Γ∗, applicable to non-Newtonian viscoplastic flows as a method for predicting fiber orientation from the accumulated strain induced by the flow. The. model was calibrated with the data obtained from the PTV measurements in 0.2% Carbopol, and was then tested by feeding it with the accumulated strain recovered by PIV in the flow without fibers. The prediction was correct within a tolerance of ±5◦, so it is concluded that the Advani-Tucker model, or a reduced form of it, allows the final alignment of groups of fibers to be predicted from the accumulated strain they are expected to experience. | |
| dc.description.ia_keyword | fibers, fiber, model, viscoplastic, flows, carbopol, high | |
| dc.identifier.citation | Wolff Casanova, L. (2026). A predictive model for fiber orientation dynamics in viscoplastic flows from experimental PIV and PTV on Carbopol as UHPC analogue [Master's thesis, Universidad de los Andes]. Repositorio Institucional UANDES. https://repositorio.uandes.cl/handle/123456789/70607 | |
| dc.identifier.uri | https://repositorio.uandes.cl/handle/123456789/70607 | |
| dc.language.iso | en | |
| dc.publisher | Universidad de los Andes, Chile | |
| dc.rights | Acceso abierto | |
| dc.rights.license | CC BY-SA 4.0 | |
| dc.rights.uri | https://creativecommons.org/licenses/by-sa/4.0/ | |
| dc.subject | Ultra-High-Performance Concrete | |
| dc.subject | Fiber Orientation | |
| dc.subject | Viscoplastic Flows | |
| dc.subject | Particle Image Velocimetry | |
| dc.subject | Particle Tracking Velocimetry | |
| dc.subject.ia_ods | ODS 9: Industria, innovación e infraestructura | |
| dc.subject.ia_oecd1n | Ingeniería y Tecnología | |
| dc.subject.ia_oecd2n | Ingeniería Mecánica | |
| dc.subject.ia_oecd3n | Ingeniería Mecánica | |
| dc.title | A Predictive Model for Fiber Orientation Dynamics in Viscoplastic Flows from Experimental PIV and PTV on Carbopol as UHPC Analogue | |
| dc.type | Tesis | |
| dc.type.coar | http://purl.org/coar/resource_type/c_bdcc |