{"id":{"repo_id":"cape-town","oai_identifier":"oai:open.uct.ac.za:11427/25388"},"canonical_url":"https://search.dev.ndltd.org/etd/cape-town/oai:open.uct.ac.za:11427/25388","repository":{"repo_id":"cape-town","name":"University of Cape Town","base_url":"https://open.uct.ac.za/oai/request"},"display":{"title":"Computational aeroacoustic modelling using hybrid RANS/LES methods with modified acoustic analogies","abstract":"This study considers a numerical approach to identifying noise mechanisms in tandem cylinders to understand aircraft landing gear as a primary contributor to airframe noise during approach and landing. Fluctuations in the flow properties induced by turbulence are computed as well as the corresponding propagations. A hybrid IDDES turbulence model is employed, to compute the boundary layer and fluctuations in the flow properties. Larsson et al. modified Curle's analogy leading to the derivation of a version of Curle's analogy that makes use of strictly time derivatives which has been proven to be less sensitive to numerical errors. Brentner and Farassat derived a formulation of the Ffowcs-Williams and Hawkings analogy for a permeable surface enclosing the acoustic sources which accounts for the quadrupole acoustic sources in the flow without the costly calculation of a volume integral. This study will consider the impact of neglecting the volume sources through a comparison of the two modified versions of Curle's and FWH analogies with the results of other CFD practitioners as well as experimental data.","abstract_html":"This study considers a numerical approach to identifying noise mechanisms in tandem cylinders to understand aircraft landing gear as a primary contributor to airframe noise during approach and landing. Fluctuations in the flow properties induced by turbulence are computed as well as the corresponding propagations. A hybrid IDDES turbulence model is employed, to compute the boundary layer and fluctuations in the flow properties. Larsson et al. modified Curle's analogy leading to the derivation of a version of Curle's analogy that makes use of strictly time derivatives which has been proven to be less sensitive to numerical errors. Brentner and Farassat derived a formulation of the Ffowcs-Williams and Hawkings analogy for a permeable surface enclosing the acoustic sources which accounts for the quadrupole acoustic sources in the flow without the costly calculation of a volume integral. This study will consider the impact of neglecting the volume sources through a comparison of the two modified versions of Curle's and FWH analogies with the results of other CFD practitioners as well as experimental data.","abstract_has_math":false,"creators":["Nyandeni, Zamashobane"],"institution":"Department of Mathematics and Applied Mathematics","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Chinyoka, Tirivanhu"],"committee_chairs":[],"committee_members":[],"year":2017,"date_issued":"2017","date_published":"2017","updated_at":"2026-07-22T22:23:22Z","subjects":[],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11427/25388","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Chinyoka, Tirivanhu"]},{"key":"dc:creator","label":"Author","values":["Nyandeni, Zamashobane"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2017-09-26T14:50:08Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2017-09-26T14:50:08Z"]},{"key":"dc:date.issued","label":"Date","values":["2017"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Department of Mathematics and Applied Mathematics"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Cape Town"]},{"key":"dc:type","label":"Dc Type","values":["Master Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Masters"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["MSc"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11427/25388"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This study considers a numerical approach to identifying noise mechanisms in tandem cylinders to understand aircraft landing gear as a primary contributor to airframe noise during approach and landing. Fluctuations in the flow properties induced by turbulence are computed as well as the corresponding propagations. A hybrid IDDES turbulence model is employed, to compute the boundary layer and fluctuations in the flow properties. Larsson et al. modified Curle's analogy leading to the derivation of a version of Curle's analogy that makes use of strictly time derivatives which has been proven to be less sensitive to numerical errors. Brentner and Farassat derived a formulation of the Ffowcs-Williams and Hawkings analogy for a permeable surface enclosing the acoustic sources which accounts for the quadrupole acoustic sources in the flow without the costly calculation of a volume integral. This study will consider the impact of neglecting the volume sources through a comparison of the two modified versions of Curle's and FWH analogies with the results of other CFD practitioners as well as experimental data."]},{"key":"dc:title","label":"Title","values":["Computational aeroacoustic modelling using hybrid RANS/LES methods with modified acoustic analogies"]}]}],"canonical_facts":{"dc:contributor.advisor":["Chinyoka, Tirivanhu"],"dc:creator":["Nyandeni, Zamashobane"],"dc:date.accessioned":["2017-09-26T14:50:08Z"],"dc:date.available":["2017-09-26T14:50:08Z"],"dc:date.issued":["2017"],"dc:description.abstract":["This study considers a numerical approach to identifying noise mechanisms in tandem cylinders to understand aircraft landing gear as a primary contributor to airframe noise during approach and landing. Fluctuations in the flow properties induced by turbulence are computed as well as the corresponding propagations. A hybrid IDDES turbulence model is employed, to compute the boundary layer and fluctuations in the flow properties. Larsson et al. modified Curle's analogy leading to the derivation of a version of Curle's analogy that makes use of strictly time derivatives which has been proven to be less sensitive to numerical errors. Brentner and Farassat derived a formulation of the Ffowcs-Williams and Hawkings analogy for a permeable surface enclosing the acoustic sources which accounts for the quadrupole acoustic sources in the flow without the costly calculation of a volume integral. This study will consider the impact of neglecting the volume sources through a comparison of the two modified versions of Curle's and FWH analogies with the results of other CFD practitioners as well as experimental data."],"dc:identifier.uri":["http://hdl.handle.net/11427/25388"],"dc:language.iso":["eng"],"dc:publisher.department":["Department of Mathematics and Applied Mathematics"],"dc:publisher.institution":["University of Cape Town"],"dc:title":["Computational aeroacoustic modelling using hybrid RANS/LES methods with modified acoustic analogies"],"dc:type":["Master Thesis"],"dc:type.qualificationlevel":["Masters"],"dc:type.qualificationname":["MSc"]},"updated_at":"2026-07-22T22:23:22Z"}