Wepresentthesimulationofthedynamicsoffluid-cylinderinteractionsinanarrowthree-dimensionalchannelfilledwithaNewtonianfluid,usingaLagrangemultiplierbasedfictitiousdomainmethodologycombinedwithafiniteelementmethodandanoperatorsplittingtechnique.Asexpected,asettlingtruncatedcylinderturnsitsbroadsideperpendiculartothemainstreamdirectionandthecenterofmassmovestothecentralaxisofthechannel.Inthecaseoftwotruncatedcylinders,theyfirstmovearoundeachotherforawhileandthenstaytogetherina"T"shape.Afterthe"T"shapehasbeenformedforalongenoughtime,wefoundnovortexsheddingbehindthecylinders.Whensimulatingthefluidizationof60truncatedcylinders,wecapturedthefeaturesofinteractionsamongfluidizedcylindersasobservedinexperiments.
