STSMs approved in the 4th Grant Period
STSM Coordinator: Dariusz Asendrych
E-mail: darek@imc.pcz.czest.pl
Host: Fredrik Lundell, KTH - Royal Institute of Technology, Stockholm, SE
Period: 21/08/2014 - 31/08/2014 (COMPLETED! Download the final report)
Work Plan Summary: The main objective of this study is to conclude a series of experiments to obtain information about the pressure drops for the solid-liquid flows that were not possible during the previous STSM due to lack of time. The particles employed will be the same as the previous STMS: glass beads (Silibeads Type S) with average diameters of 0.15 and 0.5 mm for a maximum concentration of 5 % volumetric fraction, depending on the equipment limitations.
Host: Sergio Chibbaro, Institut D'Alembert Universite' Paris 6, FR
Period: 09/11/2014 - 15/11/2014 (COMPLETED! Download the final report)
Work Plan Summary: This STSM is the natural follow up of a previous STSM held during GP1 (beneficiary: Sergio Chibbaro, host: Cristian Marchioli). During the first STSM, we analyzed DNS/LES results of turbulent flows in presence of particles and micro-fibers and we characterized the statistical and geometrical nature of the filtering error committed in LES. The aim was to devise a novel modelling approach for dilute fiber suspensions. In particular, we measured the statistics of the filtering error for a range of physical parameters including fiber elongation and inertia. This allowed us a better understanding of the relative importance that turbulent coherent structures have in determining the local dynamics of fibers and led to a quantification of the dependence of fiber dynamics on fiber shape. With all this new information available, we now propose to develop a first subgrid model for particles and fibers in LES. The model should be stochastic and based on a stochastic equation of Langevin type, suitably modified to take into account the effect of the turbulent coherent structures on particle/fiber transport in wall-bounded flows. Aim of the STSM is therefore to define as accurately as possible all the terms that appear in the modified Langevin equation (namely the model), and then implement such equation into the numerical code used to perform LES of fiber-laden turbulent flow.
Host: Dariusz Asendrych, University of Czestochowa, PL
Period: 04/02/2015 - 04/04/2015 (COMPLETED! Download the final report)
Work Plan Summary: Scope of the STSM is to study torque coefficient of rigid cylinder in uniform moderate Reynolds number flow. Flow has been previously solved by Ansys Fluent.
Host: Marina Campolo, University of Udine, IT
Period: 15/03/2015 - 30/03/2015 (COMPLETED! Download the final report)
Work Plan Summary: The purpose of the STSM was to perform experiments on drag reduction according to the scheduling proposed in the cooperative benchmark proposal. Tests were performed using two new testing loops (pipes with 3 cm and 5 cm internal diameter) to evaluate the effect of drag reduction by polymers/fibers in pipes of different size. Specifically,tests have been performed using (i) aqueous solution of PEO, (ii) aqueous solution of long Nylon fibers and (iii) aqueous solution of PEO with long Nylon fibers. Different concentrations of the polymer, fibers and polymer plus fibers were tested spanning Reynolds numbers in the range 15,000-150,000. This study hopes to provide data of pressure drop versus flow rate for a significant number of test conditions (two pipe diameters, water solutions of PEO at three different concentrations, water solutions with Nylon fibers at three different concentrations, water solutions of Nylon fibers and polymers). These data will contribute to extend significantly the self-consistent data base which is the target of the international cooperative benchmark.
Host: Laurence Bergougnoux, Aix-Marseille Universite' CNRS-IUSTI, FR
Period: 07/04/2015 - 23/05/2015 (COMPLETED! Download the final report)
Work Plan Summary: The scientific objective of the present STSM is to assess the capability of currently-available simulation techniques to reproduce experimental measurements of fiber settling velocities in simplified instances of turbulent flow. In particular, we propose to simulate the motion of small elongated fibers inside an infinite array of neighbouring counter-rotating cell vortices, which resemble several features of a real turbulent flow. Such flow configuration has been considered recently by the group of Prof. Gauzzelli and Prof. Bergougnoux, at IUSTI (Aix-Marseille University), to perform for the first time accurate measurements of particle trajectories and velocities, including both spherical particles and elongated fibers. With the simulations targeted in this STSM, we aim at providing a one-to-one comparison against these experimental measurements to test the predictive capabilities of computations based on a Eulerian-Lagrangian approach, an approach that is widely used in multi-phase flow modelling of fiber suspensions. More specifically, we will be able to test the reliability of current models for the most relevant unsteady forces acting on the fibers, in particular lift force and Basset force.
Host: Panagiota Angeli, University College of London, UK
Period: 17/05/2015 - 05/06/2015 (COMPLETED! Download the final report)
Work Plan Summary: The purpose of the STSM was to perform experiments on drag reduction according to the scheduling proposed in the cooperative benchmark proposal. Tests were performed in a 14 mm test section to evaluate the effect of drag reduction by polymers/fibers. Specifically, tests have been performed using (i) aqueous solution of PEO and HPAM, (ii) aqueous solution of long Nylon fibers (L/D=120) and (iii) aqueous solution of PEO with long Nylon fibers. Different concentrations of the polymer, fibers and polymer plus fibers were tested spanning Reynolds numbers in the range 1,500-50,000. Pressure drop measurements along with PIV investigations were performed. To avoid mechanical degradation while passing through the pump, polymers have been injected by means of a Tee junction downstream the pump.
E-mail: darek@imc.pcz.czest.pl
| Beneficiary: Dr Rui Silva, DEC-FCTUC, Coimbra, PT |  |
Host: Fredrik Lundell, KTH - Royal Institute of Technology, Stockholm, SE
Period: 21/08/2014 - 31/08/2014 (COMPLETED! Download the final report)
Work Plan Summary: The main objective of this study is to conclude a series of experiments to obtain information about the pressure drops for the solid-liquid flows that were not possible during the previous STSM due to lack of time. The particles employed will be the same as the previous STMS: glass beads (Silibeads Type S) with average diameters of 0.15 and 0.5 mm for a maximum concentration of 5 % volumetric fraction, depending on the equipment limitations.
| Beneficiary: Dr Cristian Marchioli, University of Udine, IT | |
Host: Sergio Chibbaro, Institut D'Alembert Universite' Paris 6, FR
Period: 09/11/2014 - 15/11/2014 (COMPLETED! Download the final report)
Work Plan Summary: This STSM is the natural follow up of a previous STSM held during GP1 (beneficiary: Sergio Chibbaro, host: Cristian Marchioli). During the first STSM, we analyzed DNS/LES results of turbulent flows in presence of particles and micro-fibers and we characterized the statistical and geometrical nature of the filtering error committed in LES. The aim was to devise a novel modelling approach for dilute fiber suspensions. In particular, we measured the statistics of the filtering error for a range of physical parameters including fiber elongation and inertia. This allowed us a better understanding of the relative importance that turbulent coherent structures have in determining the local dynamics of fibers and led to a quantification of the dependence of fiber dynamics on fiber shape. With all this new information available, we now propose to develop a first subgrid model for particles and fibers in LES. The model should be stochastic and based on a stochastic equation of Langevin type, suitably modified to take into account the effect of the turbulent coherent structures on particle/fiber transport in wall-bounded flows. Aim of the STSM is therefore to define as accurately as possible all the terms that appear in the modified Langevin equation (namely the model), and then implement such equation into the numerical code used to perform LES of fiber-laden turbulent flow.
| Beneficiary: Dr Jari Kolehmainen, Tampere University of Technology, Tampere, FI | |
Host: Dariusz Asendrych, University of Czestochowa, PL
Period: 04/02/2015 - 04/04/2015 (COMPLETED! Download the final report)
Work Plan Summary: Scope of the STSM is to study torque coefficient of rigid cylinder in uniform moderate Reynolds number flow. Flow has been previously solved by Ansys Fluent.
| Beneficiary: Mr Lawrence Edomwonyi-Otu, University College of London, UK | |
Host: Marina Campolo, University of Udine, IT
Period: 15/03/2015 - 30/03/2015 (COMPLETED! Download the final report)
Work Plan Summary: The purpose of the STSM was to perform experiments on drag reduction according to the scheduling proposed in the cooperative benchmark proposal. Tests were performed using two new testing loops (pipes with 3 cm and 5 cm internal diameter) to evaluate the effect of drag reduction by polymers/fibers in pipes of different size. Specifically,tests have been performed using (i) aqueous solution of PEO, (ii) aqueous solution of long Nylon fibers and (iii) aqueous solution of PEO with long Nylon fibers. Different concentrations of the polymer, fibers and polymer plus fibers were tested spanning Reynolds numbers in the range 15,000-150,000. This study hopes to provide data of pressure drop versus flow rate for a significant number of test conditions (two pipe diameters, water solutions of PEO at three different concentrations, water solutions with Nylon fibers at three different concentrations, water solutions of Nylon fibers and polymers). These data will contribute to extend significantly the self-consistent data base which is the target of the international cooperative benchmark.
| Beneficiary: Mr Diego Dotto, University of Udine, IT | |
Host: Laurence Bergougnoux, Aix-Marseille Universite' CNRS-IUSTI, FR
Period: 07/04/2015 - 23/05/2015 (COMPLETED! Download the final report)
Work Plan Summary: The scientific objective of the present STSM is to assess the capability of currently-available simulation techniques to reproduce experimental measurements of fiber settling velocities in simplified instances of turbulent flow. In particular, we propose to simulate the motion of small elongated fibers inside an infinite array of neighbouring counter-rotating cell vortices, which resemble several features of a real turbulent flow. Such flow configuration has been considered recently by the group of Prof. Gauzzelli and Prof. Bergougnoux, at IUSTI (Aix-Marseille University), to perform for the first time accurate measurements of particle trajectories and velocities, including both spherical particles and elongated fibers. With the simulations targeted in this STSM, we aim at providing a one-to-one comparison against these experimental measurements to test the predictive capabilities of computations based on a Eulerian-Lagrangian approach, an approach that is widely used in multi-phase flow modelling of fiber suspensions. More specifically, we will be able to test the reliability of current models for the most relevant unsteady forces acting on the fibers, in particular lift force and Basset force.
| Beneficiary: Dr Mattia Simeoni, University of Udine, IT | |
Host: Panagiota Angeli, University College of London, UK
Period: 17/05/2015 - 05/06/2015 (COMPLETED! Download the final report)
Work Plan Summary: The purpose of the STSM was to perform experiments on drag reduction according to the scheduling proposed in the cooperative benchmark proposal. Tests were performed in a 14 mm test section to evaluate the effect of drag reduction by polymers/fibers. Specifically, tests have been performed using (i) aqueous solution of PEO and HPAM, (ii) aqueous solution of long Nylon fibers (L/D=120) and (iii) aqueous solution of PEO with long Nylon fibers. Different concentrations of the polymer, fibers and polymer plus fibers were tested spanning Reynolds numbers in the range 1,500-50,000. Pressure drop measurements along with PIV investigations were performed. To avoid mechanical degradation while passing through the pump, polymers have been injected by means of a Tee junction downstream the pump.