A modified viscosity approach for shear thinning lubricants

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buir.contributor.authorHumayun, Ahmed
buir.contributor.authorBiancofiore, Luca
buir.contributor.orcidHumayun, Ahmed|0000-0002-5560-1802
buir.contributor.orcidBiancofiore, Luca|0000-0001-7159-7965
dc.citation.epage21en_US
dc.citation.issueNumber10en_US
dc.citation.spage1en_US
dc.citation.volumeNumber34en_US
dc.contributor.authorHumayun, Ahmed
dc.contributor.authorBiancofiore, Luca
dc.date.accessioned2023-02-23T08:25:23Z
dc.date.available2023-02-23T08:25:23Z
dc.date.issued2022-10-04
dc.departmentDepartment of Mechanical Engineeringen_US
dc.description.abstractLubrication is essential to minimize wear and friction between contacting surfaces in relative motion. Oil based lubricants are often enhanced via polymer additives to minimize self-degradation due to the shear thinning effect. Therefore, an accurate estimate of the load carrying capacity of the thin lubricating film requires careful modeling of shear thinning. Available models such as the generalized Reynolds equation (GR) and the approximate shear distribution have drawbacks such as large computational time and poor accuracy, respectively. In this work, we present a new approach, i.e., the modified viscosity (MV) model, based on calculating the strain rate only in one point along the vertical direction. We investigate, for both MV and GR, the load, the maximum pressure, and the computational time for (i) sliding (non-cavitating) contacts, (ii) cavitating, and (iii) squeezing contacts. We observe that the computational time is reduced (i) considerably for non-cavitating sliding and rolling contacts and (ii) by several orders of magnitudes for cavitating and squeezing contacts. Furthermore, the accuracy of MV is comparable with the GR model within an appreciable range of bearing numbers. Finally, for each type of boundary motion, we have determined the optimal vertical location to calculate the shear strain rate for MV; while this optimal value is close to half the height of the contact for sliding configurations, for rolling dominated and squeezing contacts it is around one quarter (or three quarter) of their height. We finally provide an analysis to a priori estimate the optimal location of the strain rate.en_US
dc.description.provenanceSubmitted by Samet Emre (samet.emre@bilkent.edu.tr) on 2023-02-23T08:25:23Z No. of bitstreams: 1 A _modified _viscosity _approach _for _shear _thinning _lubricants.pdf: 4200927 bytes, checksum: 4c2bf92221e370d9b2056d99aad77e53 (MD5)en
dc.description.provenanceMade available in DSpace on 2023-02-23T08:25:23Z (GMT). No. of bitstreams: 1 A _modified _viscosity _approach _for _shear _thinning _lubricants.pdf: 4200927 bytes, checksum: 4c2bf92221e370d9b2056d99aad77e53 (MD5) Previous issue date: 2022-10-04en
dc.identifier.doi10.1063/5.0108379en_US
dc.identifier.eissn1089-7666
dc.identifier.urihttp://hdl.handle.net/11693/111621
dc.language.isoEnglishen_US
dc.publisherAIP Publishing LLCen_US
dc.relation.isversionofhttps://doi.org/10.1063/5.0108379en_US
dc.source.titlePhysics of Fluidsen_US
dc.titleA modified viscosity approach for shear thinning lubricantsen_US
dc.typeArticleen_US

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