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SR13 Mecānica dos Fluidos |
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Title:
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THE DISPLACEMENT IN ORIGIN FOR THE THERMAL TURBULENT BOUNDARY LAYER
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Summary :
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THE PRESENT WORK DISCUSSES THE DYNAMIC AND THERMAL BEHAVIOUR OF FLOWS THAT DEVELOP OVER SURFACES THAT PRESENT A SUDDEN CHANGE IN SURFACE ROUGHNESS AND TEMPERATURE. THE THEORY USES THE CONCEPT OF THE DISPLACEMENT IN ORIGIN TO PROPOSE A NEW EXPRESSION FOR THE LOGARITHMIC REGION OF THE THERMAL TURBULENT BOUNDARY LAYER THAT LEADS TO AN ALGEBRAIC EQUATION FOR THE ESTIMATION OF STANTON NUMBER. THE NEW EXPRESSION IS OF UNIVERSAL APPLICABILITY, BEING INDEPENDENT OF THE TYPE OF ROUGH SURFACE -- IF OF THE TYPES ``K OR ``D -- CONSIDERED. THE PRESENT FORMULATION IS SHOWN TO BE APPROPRIATE FOR USE AS WALL BOUNDARY CONDITIONS IN TWO-EQUATION DIFFERENTIAL FORMULATIONS OF THE PROBLEM. EXPERIMENTS WERE ALSO CARRIED OUT TO VALIDADE THE THEORY;
MEASUREMENTS OF MEAN VELOCITY AND OF MEAN TEMPERATURE ARE PRESENTED. A REDUCTION OF THE DATA PROVIDES AN ESTIMATE OF THE SKIN-FRICTION COEFFICIENT, OF THE STANTON NUMBER, OF THE DISPLACEMENT IN ORIGIN FOR BOTH THE VELOCITY AND THE TEMPERATURE PROFILES. ALL THESE PARAMETERS WERE CALCULATED BASED ON THE CHART METHOD OF PERRY AND JOUBERT(1963) AND ON A BALANCE OF THE INTEGRAL MOMENTUM EQUATION. THE PAPER COMPARES THE PRESENT DATA WITH THE THEORY, SHOWING HOW ANY ANALOGY CAN BE DRAWN BETWEEN THE VELOCITY AND THE TEMPERATURE FIELDS.
KEY WORDS - TURBULENCE, THERMAL BOUNDARY LAYER, ROUGHNESS, ERROR IN ORIGIN.
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Author :
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dos Santos, Sergio J. F.
Guimarćes, Joćo Henrique D.
Jian, Su 0
Silva Freire, Atila Pantalećo
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Paper View :
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