CFD Simulations of Mixing using a Magnetically Driven Impeller- Method Development and Validation Study

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dc.contributor.authorOlofsson, Caroline
dc.contributor.authorSundell, Emma
dc.contributor.departmentChalmers tekniska högskola / Institutionen för mekanik och maritima vetenskapersv
dc.contributor.departmentChalmers University of Technology / Department of Mechanics and Maritime Sciencesen
dc.date.accessioned2019-07-03T14:58:48Z
dc.date.available2019-07-03T14:58:48Z
dc.date.issued2019
dc.description.abstractMixing with impellers is common in many industries. By using CFD methods, more knowledge about the mixing process can be gained since it is relatively difficult to examine experimentally. Two common turbulence models used for active mixing are the RANS and LES models. RANS methods have the advantage of being relatively cheap in terms of computational effort, whereas the more demanding LES method usually results in higher accuracy. FS Dynamics has performed CFD simulations of active mixing using a RANS method. In this study, the purpose was to improve and validate this existing method. The method has been extended by implementing LES as turbulence model. The LES was implemented together with wall functions to lower the computational demand. A tracer, inserted using two different methods, has been used for tracking the mixing processes. The first method replaces some water inside the tank with a fixed volume of tracer. The second method has an inlet of tracer to mimic pouring from physical tests, which were also conducted during this project. Both methods were used for the RANS simulations whereas only the second method was used for LES. Using a fixed volume of tracer placed beneath the surface resulted in a mixing process starting with a higher concentration at the top, spreading downwards. Using an inlet of tracer resulted in a higher tracer concentration in the bottom of the tank, which was then mixed upwards. Regarding the mixing time, the LES gave results that correspond to the physical tests and the RANS model overpredicted the mixing time by 50%. The robustness of the method using a fixed volume of tracer was evaluated by changing both the volume of tracer and its position and shape. Changing the volume from approximately 3 to 25 litres did not affect the mixing time substantially. Using different shapes and positions resulted in varying mixing time results. Changing the Schmidt number between 1 8000 or the dynamic viscosity between approximately 0:9 10 3 1:7 10 3 kg/ms did not affect the mixing times.
dc.identifier.urihttps://hdl.handle.net/20.500.12380/256474
dc.language.isoeng
dc.relation.ispartofseriesExamensarbete - Institutionen för mekanik och maritima vetenskaper : 2018:98
dc.setspec.uppsokTechnology
dc.subjectStrömningsmekanik och akustik
dc.subjectHållbar utveckling
dc.subjectLivsvetenskaper
dc.subjectFluid Mechanics and Acoustics
dc.subjectSustainable Development
dc.subjectLife Science
dc.titleCFD Simulations of Mixing using a Magnetically Driven Impeller- Method Development and Validation Study
dc.type.degreeExamensarbete för masterexamensv
dc.type.degreeMaster Thesisen
dc.type.uppsokH
local.programmeApplied mechanics (MPAME), MSc
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