{"id":{"repo_id":"brazil-uerj","oai_identifier":"oai:pantheon.ufrj.br:11422/3988"},"canonical_url":"https://search.dev.ndltd.org/etd/brazil-uerj/oai:pantheon.ufrj.br:11422/3988","repository":{"repo_id":"brazil-uerj","name":"Brazil UERJ","base_url":"https://pantheon.ufrj.br/oai/request"},"display":{"title":"Investigações sobre um esquema numérico desacoplado para modelos de circulação","abstract":"The numerical modelation by the means of finite elements can represent the frontiers of an irregular water body more eficiently than those models employing finit differences. However, finit differences models are usually solved through highly efficient algorithims, such as the ADI (Alternate Direction Implicit). Through an uncoupling in the calculation of the multiple variables (e.g. water level elevation, velocity components, salinity, etc ... ) it is possible to reduce the problem to multiple solutions of tridiagonal systems. Such algoritims, unfortunatly, are not useful in the case of finit elements, what increases its computational costs. The present thesis proposes a numerical algoritm which solves the equations of movement by making successive substitutions in the continuity equation, allowing uncoupling, even for finite elements, with great efficiency. The results of the preliminary investigation are presented, in which, in order to test the algorithim feasibility, two finite differences models for the simulation of the flow conditions in tidal canals were used, based on a one dimensional mathematics formulation. One of them solves the governant equations in an coupled way, and the other uses the proposed uncoupled algorithim. More rigorous numerical stability conditions were then verified in using the un-coupled model, but specifically in the simulations of extreme cases (with Courrant number already highly valued). For usual simulation conditions, the uncoupled model proposed was almost effectively equivalent to the conventional coupled model, concerning both, numerical process and results' precision.Such results allow the cautelous prevision of excelent possibilities concerning the extension of this technique to multidimensional circulation models, even using finite elements algorithims, leading to a significant economy of memory space and processing time.","abstract_html":"The numerical modelation by the means of finite elements can represent the frontiers of an irregular water body more eficiently than those models employing finit differences. However, finit differences models are usually solved through highly efficient algorithims, such as the ADI (Alternate Direction Implicit). Through an uncoupling in the calculation of the multiple variables (e.g. water level elevation, velocity components, salinity, etc ... ) it is possible to reduce the problem to multiple solutions of tridiagonal systems. Such algoritims, unfortunatly, are not useful in the case of finit elements, what increases its computational costs. The present thesis proposes a numerical algoritm which solves the equations of movement by making successive substitutions in the continuity equation, allowing uncoupling, even for finite elements, with great efficiency. The results of the preliminary investigation are presented, in which, in order to test the algorithim feasibility, two finite differences models for the simulation of the flow conditions in tidal canals were used, based on a one dimensional mathematics formulation. One of them solves the governant equations in an coupled way, and the other uses the proposed uncoupled algorithim. More rigorous numerical stability conditions were then verified in using the un-coupled model, but specifically in the simulations of extreme cases (with Courrant number already highly valued). For usual simulation conditions, the uncoupled model proposed was almost effectively equivalent to the conventional coupled model, concerning both, numerical process and results' precision.Such results allow the cautelous prevision of excelent possibilities concerning the extension of this technique to multidimensional circulation models, even using finite elements algorithims, leading to a significant economy of memory space and processing time.","abstract_has_math":false,"creators":["Vasconcellos Filho, Fernando Montenegro Cabral de"],"institution":"Universidade Federal do Rio de Janeiro","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Rosman, Paulo Cesar Colonna"],"committee_chairs":[],"committee_members":[],"year":1991,"date_issued":"1991","date_published":"1991","updated_at":"2026-07-24T01:16:12Z","subjects":["Engenharia Civil"],"languages":["por"],"rights":["Acesso Aberto"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11422/3988","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Rosman, Paulo Cesar Colonna"]},{"key":"dc:creator","label":"Author","values":["Vasconcellos Filho, Fernando Montenegro Cabral de"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2018-05-23T16:15:51Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-05-16T03:05:31Z"]},{"key":"dc:date.issued","label":"Date","values":["1991"]},{"key":"dc:publisher","label":"Institution","values":["Universidade Federal do Rio de Janeiro"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Instituto Alberto Luiz Coimbra de Pós-Graduação e Pesquisa de Engenharia"]},{"key":"dc:type","label":"Dc Type","values":["Dissertação"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Engenharia Civil"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["por"]},{"key":"dc:rights","label":"Dc Rights","values":["Acesso Aberto"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11422/3988"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The numerical modelation by the means of finite elements can represent the frontiers of an irregular water body more eficiently than those models employing finit differences. However, finit differences models are usually solved through highly efficient algorithims, such as the ADI (Alternate Direction Implicit). Through an uncoupling in the calculation of the multiple variables (e.g. water level elevation, velocity components, salinity, etc ... ) it is possible to reduce the problem to multiple solutions of tridiagonal systems. Such algoritims, unfortunatly, are not useful in the case of finit elements, what increases its computational costs. The present thesis proposes a numerical algoritm which solves the equations of movement by making successive substitutions in the continuity equation, allowing uncoupling, even for finite elements, with great efficiency. The results of the preliminary investigation are presented, in which, in order to test the algorithim feasibility, two finite differences models for the simulation of the flow conditions in tidal canals were used, based on a one dimensional mathematics formulation. One of them solves the governant equations in an coupled way, and the other uses the proposed uncoupled algorithim. More rigorous numerical stability conditions were then verified in using the un-coupled model, but specifically in the simulations of extreme cases (with Courrant number already highly valued). For usual simulation conditions, the uncoupled model proposed was almost effectively equivalent to the conventional coupled model, concerning both, numerical process and results' precision.Such results allow the cautelous prevision of excelent possibilities concerning the extension of this technique to multidimensional circulation models, even using finite elements algorithims, leading to a significant economy of memory space and processing time."]},{"key":"dc:title","label":"Title","values":["Investigações sobre um esquema numérico desacoplado para modelos de circulação"]}]}],"canonical_facts":{"dc:contributor.advisor":["Rosman, Paulo Cesar Colonna"],"dc:creator":["Vasconcellos Filho, Fernando Montenegro Cabral de"],"dc:date.accessioned":["2018-05-23T16:15:51Z"],"dc:date.available":["2026-05-16T03:05:31Z"],"dc:date.issued":["1991"],"dc:description.abstract":["The numerical modelation by the means of finite elements can represent the frontiers of an irregular water body more eficiently than those models employing finit differences. However, finit differences models are usually solved through highly efficient algorithims, such as the ADI (Alternate Direction Implicit). Through an uncoupling in the calculation of the multiple variables (e.g. water level elevation, velocity components, salinity, etc ... ) it is possible to reduce the problem to multiple solutions of tridiagonal systems. Such algoritims, unfortunatly, are not useful in the case of finit elements, what increases its computational costs. The present thesis proposes a numerical algoritm which solves the equations of movement by making successive substitutions in the continuity equation, allowing uncoupling, even for finite elements, with great efficiency. The results of the preliminary investigation are presented, in which, in order to test the algorithim feasibility, two finite differences models for the simulation of the flow conditions in tidal canals were used, based on a one dimensional mathematics formulation. One of them solves the governant equations in an coupled way, and the other uses the proposed uncoupled algorithim. More rigorous numerical stability conditions were then verified in using the un-coupled model, but specifically in the simulations of extreme cases (with Courrant number already highly valued). For usual simulation conditions, the uncoupled model proposed was almost effectively equivalent to the conventional coupled model, concerning both, numerical process and results' precision.Such results allow the cautelous prevision of excelent possibilities concerning the extension of this technique to multidimensional circulation models, even using finite elements algorithims, leading to a significant economy of memory space and processing time."],"dc:identifier.uri":["http://hdl.handle.net/11422/3988"],"dc:language":["por"],"dc:publisher":["Universidade Federal do Rio de Janeiro"],"dc:publisher.department":["Instituto Alberto Luiz Coimbra de Pós-Graduação e Pesquisa de Engenharia"],"dc:rights":["Acesso Aberto"],"dc:subject":["Engenharia Civil"],"dc:title":["Investigações sobre um esquema numérico desacoplado para modelos de circulação"],"dc:type":["Dissertação"]},"updated_at":"2026-07-24T01:16:12Z"}