"Coextrusion polyethylene based flows have been analyzed through finite element method by the use of the modified Leonov model. It has been found that the onset of wave type of interfacial instabilities is driven by the discontinuity and non-monotonicity"@en . . . "2009-10-22+02:00"^^ . . . . "Investigation of unusual flow phenomena of non-Newtonian fluids in complex geometries"@en . . . "2008-04-25+02:00"^^ . . "http://www.isvav.cz/projectDetail.do?rowId=GA103/06/1033"^^ . . . . "P\u0159i soub\u011B\u017En\u00E9m vytla\u010Dov\u00E1n\u00ED dvou a v\u00EDce viskoelastick\u00FDch polymern\u00EDch tavenin doch\u00E1z\u00ED ke vzniku neobvykl\u00FDch tokov\u00FDch jev\u016F (nap\u0159. meziplo\u0161n\u00E9 nestability) destabilizuj\u00EDch tento proces. C\u00EDlem navrhovan\u00E9ho projektu je definovat mechanismus n\u00E1stupu nestabiln\u00EDho chov\u00E1n\u00ED mezi jednotliv\u00FDmi vrstvami a d\u00E1t do souvzta\u017Enosti veli\u010Diny charakterizuj\u00EDc\u00ED proces koextruze, u\u017Eit\u00E9 materi\u00E1ly a geometrii vytla\u010Duj\u00EDc\u00EDch hubic s c\u00EDlem optimalizovat v\u00FDrobu a ur\u010Dit kritick\u00E9 hodnoty parametr\u016F pro n\u00E1stup destabilizuj\u00EDc\u00EDch jev\u016F. Za t\u00EDmto \u00FA\u010Delem bude navr\u017Eena nov\u00E1 prediktivn\u00ED metodologie pro ur\u010Den\u00ED uveden\u00FDch nestabilit p\u0159i koextruzi polymern\u00EDch tavenin s n\u00E1sledn\u00FDm experiment\u00E1ln\u00EDm ov\u011B\u0159en\u00EDm. Nav\u00EDc, anal\u00FDza smykov\u00FDch tok\u016F vazko-elasto-plastick\u00FDch materi\u00E1l\u016F v jednoduch\u00FDch a v\u00EDcen\u00E1sobn\u011B souvisl\u00FDch oblastech (nap\u0159. v mezikru\u017E\u00ED) vy\u017Eaduje p\u0159i kvalitativn\u00EDm popisu proud\u011Bn\u00ED hlub\u0161\u00ED pozn\u00E1n\u00ED t\u00FDkaj\u00EDc\u00ED se v\u00FDskytu meze kluzu. D\u016Fraz p\u0159i \u0159e\u0161en\u00ED jednotliv\u00FDch typ\u016F Couetteova-Poiseuilleova proud\u011Bn\u00ED bude kladen na mo\u017Enost odvozen\u00ED explicitn\u00EDch vztah\u016F" . "Coextrusion of two or more viscoelastic polymer melts gives rise an unusual flow phenomena - interfacial instabilities, which strongly destabilize the process. The objective of this project is to define the onset mechanism of these undesirable phenomena and to reveal relationships between processing, materials and die design parameters with the aim of optimizing production and determining critical parameters for setting the destabilizing phenomena. A novel fully predictive modeling strategy for the interfacial instability determination will be proposed for coextrusion flows and experimentally verified. Moreover, analysis of shear flows of visco-elasto-plastic fluids in single- and multiple-connected regions (e.g. in annuli) requires more fundamental approach concerning participation of a yield stress in a qualitative description of these flows. An emphasis in the individual Couette-Poiseuille flows will be paid to a possibility of derivation of the explicit relations (as e.g."@en . "Anal\u00FDza nestandartn\u00EDch projev\u016F nenewtonsk\u00FDch kapalin p\u0159i toku v komplexn\u00EDch geometri\u00EDch" . "0"^^ . . "Coextrusion; Polymer melts; Interfacial instabilities; Visco-elasto-plastic fluids; Flow in annuli"@en . " Polymer melts" . . "1"^^ . "1"^^ . " Visco-elasto-plastic fluids" . "Proces koextruze vybran\u00FDch polyethyl\u00E9n\u016F byl modelov\u00E1n MKP s vyu\u017Eit\u00EDm modifikovan\u00E9ho Leonovova modelu. Bylo zji\u0161t\u011Bno, \u017Ee k n\u00E1stupu vlnov\u00E9ho typu meziplo\u0161n\u00FDch nestabilit v\u00FDznamn\u011B p\u0159isp\u00EDv\u00E1 diskontinu\u00E1ln\u00ED p\u0159echod norm\u00E1lov\u00FDch nap\u011Bt\u00ED ve sm\u011Bru kolm\u00E9m na rozhran"@cs . "Coextrusion" . . . "2006-01-01+01:00"^^ . "GA103/06/1033" . "17"^^ . "17"^^ . "2008-12-31+01:00"^^ . . " Interfacial instabilities" . . .