{"title":"Withdrawal: Numerical studies of a buoy system; a comparison between LES and SAS","authors":"M. Ilie, K. Harris","doi":"10.2514/6.2018-3537.C1","DOIUrl":"https://doi.org/10.2514/6.2018-3537.C1","url":null,"abstract":"","PeriodicalId":93061,"journal":{"name":"48th AIAA Fluid Dynamics Conference 2018 : held at the AIAA Aviation Forum 2018 : Atlanta, Georgia, USA, 25-29 June 2018. AIAA Fluid Dynamics Conference (48th : 2018 : Atlanta, Ga.)","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78740965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Rigid Body Response of a Mach 2 Shock Train to Downstream Forcing","authors":"Louis M. Edelman, M. Gamba","doi":"10.2514/6.2018-3542","DOIUrl":"https://doi.org/10.2514/6.2018-3542","url":null,"abstract":"","PeriodicalId":93061,"journal":{"name":"48th AIAA Fluid Dynamics Conference 2018 : held at the AIAA Aviation Forum 2018 : Atlanta, Georgia, USA, 25-29 June 2018. AIAA Fluid Dynamics Conference (48th : 2018 : Atlanta, Ga.)","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72960623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Concentration Measurements in Simulations of the Variable Density Mixing Layer","authors":"Jiang Huang, W. A. McMullan","doi":"10.2514/6.2018-3865","DOIUrl":"https://doi.org/10.2514/6.2018-3865","url":null,"abstract":"","PeriodicalId":93061,"journal":{"name":"48th AIAA Fluid Dynamics Conference 2018 : held at the AIAA Aviation Forum 2018 : Atlanta, Georgia, USA, 25-29 June 2018. AIAA Fluid Dynamics Conference (48th : 2018 : Atlanta, Ga.)","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73338018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Nicholson, Chao Zhang, L. Duan, M. Malik, Fei Li, A. Uzun
Direct numerical simulations (DNS) are performed to examine the receptivity to roughness in a spatially developing three-dimensional boundary layer over an infinite-swept natural-laminar-flow wing at a freestream Mach number of 0 . 75 and a chord Reynolds number of approximately 25 million based on the long, swept chord. Stationary crossflow disturbances are excited by applying either critically spaced discrete cylinders of micron size or naturally occurring distributed roughness in the leading-edge region. The DNS data show that the spanwise spectral content of the excited crossflow disturbances is highly dependent upon the shape of roughness elements, and the initial growth of the crossflow structures is a nonlinear function of the element height. The linear growth rate of the excited crossflow disturbances predicted by DNS shows good agreement with linear parab-olized stability equations. The receptivity study lays the foundation for investigating the stabilization of the naturally most unstable steady crossflow mode by using spanwise periodic DREs
{"title":"Direct Numerical Simulation of Receptivity to Roughness in a Swept-Wing Boundary Layer at High Reynolds Numbers","authors":"G. Nicholson, Chao Zhang, L. Duan, M. Malik, Fei Li, A. Uzun","doi":"10.2514/6.2018-3076","DOIUrl":"https://doi.org/10.2514/6.2018-3076","url":null,"abstract":"Direct numerical simulations (DNS) are performed to examine the receptivity to roughness in a spatially developing three-dimensional boundary layer over an infinite-swept natural-laminar-flow wing at a freestream Mach number of 0 . 75 and a chord Reynolds number of approximately 25 million based on the long, swept chord. Stationary crossflow disturbances are excited by applying either critically spaced discrete cylinders of micron size or naturally occurring distributed roughness in the leading-edge region. The DNS data show that the spanwise spectral content of the excited crossflow disturbances is highly dependent upon the shape of roughness elements, and the initial growth of the crossflow structures is a nonlinear function of the element height. The linear growth rate of the excited crossflow disturbances predicted by DNS shows good agreement with linear parab-olized stability equations. The receptivity study lays the foundation for investigating the stabilization of the naturally most unstable steady crossflow mode by using spanwise periodic DREs","PeriodicalId":93061,"journal":{"name":"48th AIAA Fluid Dynamics Conference 2018 : held at the AIAA Aviation Forum 2018 : Atlanta, Georgia, USA, 25-29 June 2018. AIAA Fluid Dynamics Conference (48th : 2018 : Atlanta, Ga.)","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75578025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Instabilities in Mach 6 Flow over a Cone with a Swept Fin","authors":"Anthony L. Knutson, G. Sidharth, G. Candler","doi":"10.2514/6.2018-3071","DOIUrl":"https://doi.org/10.2514/6.2018-3071","url":null,"abstract":"","PeriodicalId":93061,"journal":{"name":"48th AIAA Fluid Dynamics Conference 2018 : held at the AIAA Aviation Forum 2018 : Atlanta, Georgia, USA, 25-29 June 2018. AIAA Fluid Dynamics Conference (48th : 2018 : Atlanta, Ga.)","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79940844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Heat and Fluid Flow around a Cylinder in Wake","authors":"Farhan Zafar, M. Alam","doi":"10.2514/6.2018-3083","DOIUrl":"https://doi.org/10.2514/6.2018-3083","url":null,"abstract":"","PeriodicalId":93061,"journal":{"name":"48th AIAA Fluid Dynamics Conference 2018 : held at the AIAA Aviation Forum 2018 : Atlanta, Georgia, USA, 25-29 June 2018. AIAA Fluid Dynamics Conference (48th : 2018 : Atlanta, Ga.)","volume":"15 3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80482816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. F. J. Colmenares, S. Poroseva, Y. Peet, S. Murman
Understanding spatial development of a turbulent mixing layer is essential for various aerospace applications. However, multiple factors affect physics of this flow, making it difficult to reproduce results of experiments in simulations. The current study investigates sensitivity of direct numerical simulation (DNS) of such a flow to computational parameters. In particular, effects of a time step in a temporal discretization scheme, dimensions of the computational domain, and the laminar boundary layer characteristics at the splitter plate trailing edge are considered. Flow conditions used in DNS are close to those from the experiments by Bell & Mehta (1990), where untripped boundary layers co-flowing on both sides of a splitter plate mix downstream the plate. No artificial perturbations are used in simulations to trigger the flow transition to turbulence. DNS are conducted using the spectralelement code Nek5000.
{"title":"Analysis of uncertainty sources in DNS of a turbulent mixing layer using Nek5000","authors":"D. F. J. Colmenares, S. Poroseva, Y. Peet, S. Murman","doi":"10.2514/6.2018-3226","DOIUrl":"https://doi.org/10.2514/6.2018-3226","url":null,"abstract":"Understanding spatial development of a turbulent mixing layer is essential for various aerospace applications. However, multiple factors affect physics of this flow, making it difficult to reproduce results of experiments in simulations. The current study investigates sensitivity of direct numerical simulation (DNS) of such a flow to computational parameters. In particular, effects of a time step in a temporal discretization scheme, dimensions of the computational domain, and the laminar boundary layer characteristics at the splitter plate trailing edge are considered. Flow conditions used in DNS are close to those from the experiments by Bell & Mehta (1990), where untripped boundary layers co-flowing on both sides of a splitter plate mix downstream the plate. No artificial perturbations are used in simulations to trigger the flow transition to turbulence. DNS are conducted using the spectralelement code Nek5000.","PeriodicalId":93061,"journal":{"name":"48th AIAA Fluid Dynamics Conference 2018 : held at the AIAA Aviation Forum 2018 : Atlanta, Georgia, USA, 25-29 June 2018. AIAA Fluid Dynamics Conference (48th : 2018 : Atlanta, Ga.)","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81989269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Optimum gaits of 2D thunniform locomotion for efficient swimming and performance of fish pair","authors":"Yiqin Xu, Y. Peet","doi":"10.2514/6.2018-2915","DOIUrl":"https://doi.org/10.2514/6.2018-2915","url":null,"abstract":"","PeriodicalId":93061,"journal":{"name":"48th AIAA Fluid Dynamics Conference 2018 : held at the AIAA Aviation Forum 2018 : Atlanta, Georgia, USA, 25-29 June 2018. AIAA Fluid Dynamics Conference (48th : 2018 : Atlanta, Ga.)","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85564141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Film cooling is used in a wide variety of engineering applications for protection of surfaces from hot or combusting gases. The design of more efficient thin film cooling geometries/configurations could be facilitated by an ability to accurately model and predict the effectiveness of current designs using computational fluid dynamics (CFD) code predictions. Hence, a benchmark set of flow field property data were obtained for use in assessing current CFD capabilities and for development of better turbulence models. Both Particle Image Velocimetry (PIV) and spontaneous rotational Raman scattering (SRS) spectroscopy were used to acquire high quality, spatially-resolved measurements of the mean velocity, turbulence intensity and also the mean temperature and normalized root mean square (rms) temperatures in a single injector cooling flow arrangement. In addition to flowfield measurements, thermocouple measurements on the plate surface enabled estimates of the film effectiveness. Raman spectra in air were obtained across a matrix of radial and axial locations downstream from a 68.07 mm square nozzle blowing heated air over a range of temperatures and Mach numbers, across a 30.48cm long plate equipped with a single injector cooling hole. In addition, both centerline streamwise 2-component PIV and cross-stream 3-component Stereo PIV data at 15 axial stations were collected in the same flows. The velocity and temperature data were then compared against Wind-US CFD code predictions for the same flow conditions. The results of this and planned follow-on studies will support NASA’s development and assessment of turbulence models for heated flows.
{"title":"PIV and Rotational Raman-Based Temperature Measurements for CFD Validation in a Single Injector Cooling Flow","authors":"M. Wernet, N. Georgiadis, R. J. Locke","doi":"10.2514/6.2018-3857","DOIUrl":"https://doi.org/10.2514/6.2018-3857","url":null,"abstract":"Film cooling is used in a wide variety of engineering applications for protection of surfaces from hot or combusting gases. The design of more efficient thin film cooling geometries/configurations could be facilitated by an ability to accurately model and predict the effectiveness of current designs using computational fluid dynamics (CFD) code predictions. Hence, a benchmark set of flow field property data were obtained for use in assessing current CFD capabilities and for development of better turbulence models. Both Particle Image Velocimetry (PIV) and spontaneous rotational Raman scattering (SRS) spectroscopy were used to acquire high quality, spatially-resolved measurements of the mean velocity, turbulence intensity and also the mean temperature and normalized root mean square (rms) temperatures in a single injector cooling flow arrangement. In addition to flowfield measurements, thermocouple measurements on the plate surface enabled estimates of the film effectiveness. Raman spectra in air were obtained across a matrix of radial and axial locations downstream from a 68.07 mm square nozzle blowing heated air over a range of temperatures and Mach numbers, across a 30.48cm long plate equipped with a single injector cooling hole. In addition, both centerline streamwise 2-component PIV and cross-stream 3-component Stereo PIV data at 15 axial stations were collected in the same flows. The velocity and temperature data were then compared against Wind-US CFD code predictions for the same flow conditions. The results of this and planned follow-on studies will support NASA’s development and assessment of turbulence models for heated flows.","PeriodicalId":93061,"journal":{"name":"48th AIAA Fluid Dynamics Conference 2018 : held at the AIAA Aviation Forum 2018 : Atlanta, Georgia, USA, 25-29 June 2018. AIAA Fluid Dynamics Conference (48th : 2018 : Atlanta, Ga.)","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77775976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Crossflow Stability of a Swept Flat Plate with Wavy Leading Edge","authors":"M. Owen, A. Frendi","doi":"10.2514/6.2018-3389","DOIUrl":"https://doi.org/10.2514/6.2018-3389","url":null,"abstract":"","PeriodicalId":93061,"journal":{"name":"48th AIAA Fluid Dynamics Conference 2018 : held at the AIAA Aviation Forum 2018 : Atlanta, Georgia, USA, 25-29 June 2018. AIAA Fluid Dynamics Conference (48th : 2018 : Atlanta, Ga.)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72790015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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