{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/141059"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/141059","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Modeling Droplet Impingement Dynamics on Micropillar-Arrayed Viscoelastic Substrates Through Microgeometry-Free and Multiscale Methods","abstract":"The droplet impact dynamics on micropillar-arrayed viscoelastic substrates has been thoroughly investigated by two distinct modeling methods, i.e., microgeometry-free and multiscale modeling methods. The viscoelasticity of the micropillar-arrayed substrate is characterized by a five-parameter generalized Maxwell model via the Laplace-Carson transform. In the microgeometry-free modeling, only one general domain containing all the modeled objects is constructed with the detailed geometry of micropillars omitted. In contrast, by multiscale modeling, two different geometric-scale domains are employed to investigate the deformation of individual micropillars in the smaller domain named zoomed-in domain and the effects of the deducted deformation velocity on the fluid field evolution in the larger domain called the zoomed-out domain. These two methods both have advantages and disadvantages regarding efficiency, accuracy and information completeness and emphasis. The microgeometry-free method serves as an efficient tool to rapidly determine the flow evolution after droplet impingement, while being deficient to accurately describe the individual micropillar deformation. By contrast, the multiscale method can appropriately stress this issue by constructing magnification domains along the bottom micropillar array with the entrapped gas cushioning effect evaluated, which in turn results in a more precise illustration of fluid field evolution. However, due to more details considered, this method becomes much more time consuming and requires significant computational resources. Although the microgeometry-free and multiscale modeling methods are implemented via distinct procedures, they share some common aspects such as using the general larger domain to define the macroscopic flow evolution and leveraging the generalized Maxwell model to characterize substrate viscoelasticity. This indicates that these two methods are interrelated rather than independent. Therefore, they together substantially demonstrate the evolution of droplet and the deformation of micropillar array, and significantly provide meaningful clues to understand fluid-structure interaction with enormous geometric-scale inconsistency and complex physical properties involved.","abstract_html":"The droplet impact dynamics on micropillar-arrayed viscoelastic substrates has been thoroughly investigated by two distinct modeling methods, i.e., microgeometry-free and multiscale modeling methods. The viscoelasticity of the micropillar-arrayed substrate is characterized by a five-parameter generalized Maxwell model via the Laplace-Carson transform. In the microgeometry-free modeling, only one general domain containing all the modeled objects is constructed with the detailed geometry of micropillars omitted. In contrast, by multiscale modeling, two different geometric-scale domains are employed to investigate the deformation of individual micropillars in the smaller domain named zoomed-in domain and the effects of the deducted deformation velocity on the fluid field evolution in the larger domain called the zoomed-out domain. These two methods both have advantages and disadvantages regarding efficiency, accuracy and information completeness and emphasis. The microgeometry-free method serves as an efficient tool to rapidly determine the flow evolution after droplet impingement, while being deficient to accurately describe the individual micropillar deformation. By contrast, the multiscale method can appropriately stress this issue by constructing magnification domains along the bottom micropillar array with the entrapped gas cushioning effect evaluated, which in turn results in a more precise illustration of fluid field evolution. However, due to more details considered, this method becomes much more time consuming and requires significant computational resources. Although the microgeometry-free and multiscale modeling methods are implemented via distinct procedures, they share some common aspects such as using the general larger domain to define the macroscopic flow evolution and leveraging the generalized Maxwell model to characterize substrate viscoelasticity. This indicates that these two methods are interrelated rather than independent. Therefore, they together substantially demonstrate the evolution of droplet and the deformation of micropillar array, and significantly provide meaningful clues to understand fluid-structure interaction with enormous geometric-scale inconsistency and complex physical properties involved.","abstract_has_math":false,"creators":["Li, Yang"],"institution":"Virginia Tech","degree_name":"Doctor of Philosophy","degree_level":"doctoral","degree_discipline":"Mechanical Engineering","degree_department":"Mechanical Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Cheng, Jiangtao"],"committee_members":["Paul, Mark R.","Yue, Pengtao","Liu, Yang"],"year":2026,"date_issued":"2026-01-29","date_published":"2026-01-29","updated_at":"2026-07-22T22:19:16Z","subjects":["droplet impingement","micropillar-arrayed viscoelastic substrate","droplet-gas two-phase flow","multiscale modeling"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:45540"],"render_values":[{"text":"vt_gsexam:45540","href":null,"code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/10919/141059","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Cheng, Jiangtao"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Paul, Mark R.","Yue, Pengtao","Liu, Yang"]},{"key":"dc:contributor.department","label":"Department","values":["Mechanical Engineering"]},{"key":"dc:creator","label":"Author","values":["Li, Yang"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-01-30T09:00:12Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-01-30T09:00:12Z"]},{"key":"dc:date.issued","label":"Date","values":["2026-01-29"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["droplet impingement","micropillar-arrayed viscoelastic substrate","droplet-gas two-phase flow","multiscale modeling"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:45540"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10919/141059"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The droplet impact dynamics on micropillar-arrayed viscoelastic substrates has been thoroughly investigated by two distinct modeling methods, i.e., microgeometry-free and multiscale modeling methods. The viscoelasticity of the micropillar-arrayed substrate is characterized by a five-parameter generalized Maxwell model via the Laplace-Carson transform. In the microgeometry-free modeling, only one general domain containing all the modeled objects is constructed with the detailed geometry of micropillars omitted. In contrast, by multiscale modeling, two different geometric-scale domains are employed to investigate the deformation of individual micropillars in the smaller domain named zoomed-in domain and the effects of the deducted deformation velocity on the fluid field evolution in the larger domain called the zoomed-out domain. These two methods both have advantages and disadvantages regarding efficiency, accuracy and information completeness and emphasis. The microgeometry-free method serves as an efficient tool to rapidly determine the flow evolution after droplet impingement, while being deficient to accurately describe the individual micropillar deformation. By contrast, the multiscale method can appropriately stress this issue by constructing magnification domains along the bottom micropillar array with the entrapped gas cushioning effect evaluated, which in turn results in a more precise illustration of fluid field evolution. However, due to more details considered, this method becomes much more time consuming and requires significant computational resources. Although the microgeometry-free and multiscale modeling methods are implemented via distinct procedures, they share some common aspects such as using the general larger domain to define the macroscopic flow evolution and leveraging the generalized Maxwell model to characterize substrate viscoelasticity. This indicates that these two methods are interrelated rather than independent. Therefore, they together substantially demonstrate the evolution of droplet and the deformation of micropillar array, and significantly provide meaningful clues to understand fluid-structure interaction with enormous geometric-scale inconsistency and complex physical properties involved."]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["Droplet impingement on micropillar-arrayed viscoelastic substrates entails multiscale geometric configurations and complex viscoelastic characteristics of the micropillar array, which render accurate modeling challenging, especially when the droplet-micropillar interaction and the entrapped ambient gas cushioning between neighboring micropillars are considered. This dissertation leverages two different modeling methods to investigate the spreading film evolution resulting from the droplet impact and quantify the micropillar deformation. These two methods have their own advantages and disadvantages when compared to each other. In detail, the microgeometry-free modeling method can fast simulate the droplet dynamics on micropillar-arrayed substrate under various physical conditions, while the individual micropillar deformation remains a hidden point in this modeling and can only be approximated by the deformation of specific discretization cells along the bottom boundary. On the contrary, the detailed deformation for each individual micropillar can be delineated by the multiscale modeling with constructing magnification domains, which correspond to specific portions of the bottom micropillar array within the general domain. Meanwhile, since the geometric configuration of the micropillars is constructed in the multiscale modeling, the cushioning effect of the entrapped ambient gas on the micropillar deformation can also be evaluated appropriately. Nonetheless, higher accuracy and more involved information indicate consumption of more computational resources, which should be assessed during the actual implementation. According to the modeling results by the microgeometry modeling, higher impact velocity U_i, greater ambient pressure P_a and smaller surface tension σ all contribute to a more intense splash occurrence, which is also consistent with the Kelvin-Helmholtz Instability theory. Within the multiscale modeling framework, the deformation of micropillars is computed explicitly so that both the magnitude and directional oscillations can be analyzed after droplet impingement. Furthermore, the entrapped gas cushioning can be examined through the fact that under some impact velocities, the largest deformation across various gap densities appears at a lower gap density (0.10 or 0.15) rather than at the highest gap density (0.20). This phenomenon becomes more prominent with increasing impact velocity. In essence, our investigation of droplet impingement dynamics on micropillar-arrayed substrate through the microgeometry-free and multiscale modeling methods sheds light on accurately determining the liquid-gas interface evolution and specifically computing the deformation of micropillar array. These two methods are of substantial significance and offer profound insights into future investigations of droplet impingement dynamics on microstructured viscoelastic surfaces."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Doctor of Philosophy"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Modeling Droplet Impingement Dynamics on Micropillar-Arrayed Viscoelastic Substrates Through Microgeometry-Free and Multiscale Methods"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Cheng, Jiangtao"],"dc:contributor.committeemember":["Paul, Mark R.","Yue, Pengtao","Liu, Yang"],"dc:contributor.department":["Mechanical Engineering"],"dc:creator":["Li, Yang"],"dc:date.accessioned":["2026-01-30T09:00:12Z"],"dc:date.available":["2026-01-30T09:00:12Z"],"dc:date.issued":["2026-01-29"],"dc:description.abstract":["The droplet impact dynamics on micropillar-arrayed viscoelastic substrates has been thoroughly investigated by two distinct modeling methods, i.e., microgeometry-free and multiscale modeling methods. The viscoelasticity of the micropillar-arrayed substrate is characterized by a five-parameter generalized Maxwell model via the Laplace-Carson transform. In the microgeometry-free modeling, only one general domain containing all the modeled objects is constructed with the detailed geometry of micropillars omitted. In contrast, by multiscale modeling, two different geometric-scale domains are employed to investigate the deformation of individual micropillars in the smaller domain named zoomed-in domain and the effects of the deducted deformation velocity on the fluid field evolution in the larger domain called the zoomed-out domain. These two methods both have advantages and disadvantages regarding efficiency, accuracy and information completeness and emphasis. The microgeometry-free method serves as an efficient tool to rapidly determine the flow evolution after droplet impingement, while being deficient to accurately describe the individual micropillar deformation. By contrast, the multiscale method can appropriately stress this issue by constructing magnification domains along the bottom micropillar array with the entrapped gas cushioning effect evaluated, which in turn results in a more precise illustration of fluid field evolution. However, due to more details considered, this method becomes much more time consuming and requires significant computational resources. Although the microgeometry-free and multiscale modeling methods are implemented via distinct procedures, they share some common aspects such as using the general larger domain to define the macroscopic flow evolution and leveraging the generalized Maxwell model to characterize substrate viscoelasticity. This indicates that these two methods are interrelated rather than independent. Therefore, they together substantially demonstrate the evolution of droplet and the deformation of micropillar array, and significantly provide meaningful clues to understand fluid-structure interaction with enormous geometric-scale inconsistency and complex physical properties involved."],"dc:description.abstractgeneral":["Droplet impingement on micropillar-arrayed viscoelastic substrates entails multiscale geometric configurations and complex viscoelastic characteristics of the micropillar array, which render accurate modeling challenging, especially when the droplet-micropillar interaction and the entrapped ambient gas cushioning between neighboring micropillars are considered. This dissertation leverages two different modeling methods to investigate the spreading film evolution resulting from the droplet impact and quantify the micropillar deformation. These two methods have their own advantages and disadvantages when compared to each other. In detail, the microgeometry-free modeling method can fast simulate the droplet dynamics on micropillar-arrayed substrate under various physical conditions, while the individual micropillar deformation remains a hidden point in this modeling and can only be approximated by the deformation of specific discretization cells along the bottom boundary. On the contrary, the detailed deformation for each individual micropillar can be delineated by the multiscale modeling with constructing magnification domains, which correspond to specific portions of the bottom micropillar array within the general domain. Meanwhile, since the geometric configuration of the micropillars is constructed in the multiscale modeling, the cushioning effect of the entrapped ambient gas on the micropillar deformation can also be evaluated appropriately. Nonetheless, higher accuracy and more involved information indicate consumption of more computational resources, which should be assessed during the actual implementation. According to the modeling results by the microgeometry modeling, higher impact velocity U_i, greater ambient pressure P_a and smaller surface tension σ all contribute to a more intense splash occurrence, which is also consistent with the Kelvin-Helmholtz Instability theory. Within the multiscale modeling framework, the deformation of micropillars is computed explicitly so that both the magnitude and directional oscillations can be analyzed after droplet impingement. Furthermore, the entrapped gas cushioning can be examined through the fact that under some impact velocities, the largest deformation across various gap densities appears at a lower gap density (0.10 or 0.15) rather than at the highest gap density (0.20). This phenomenon becomes more prominent with increasing impact velocity. In essence, our investigation of droplet impingement dynamics on micropillar-arrayed substrate through the microgeometry-free and multiscale modeling methods sheds light on accurately determining the liquid-gas interface evolution and specifically computing the deformation of micropillar array. These two methods are of substantial significance and offer profound insights into future investigations of droplet impingement dynamics on microstructured viscoelastic surfaces."],"dc:description.degree":["Doctor of Philosophy"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:45540"],"dc:identifier.uri":["https://hdl.handle.net/10919/141059"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["droplet impingement","micropillar-arrayed viscoelastic substrate","droplet-gas two-phase flow","multiscale modeling"],"dc:title":["Modeling Droplet Impingement Dynamics on Micropillar-Arrayed Viscoelastic Substrates Through Microgeometry-Free and Multiscale Methods"],"dc:type":["Dissertation"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Doctor of Philosophy"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:16Z"}