CONFERENCE ON FLUID DYNAMICS | Year:2015 | دوره:16 |Papers Count:19

IN THIS STUDY, WE HAVE PROVIDED A CRITERION FOR JET SLOT LOCATION IN DYNAMIC STALL MOTION OF AN AIRFOIL AT HIGH REYNOLDS NUMBER 1´106, FOR ACTIVE FLOW CONTROL (AFC) PURPOSES. THE AIRFOIL IS SYMMETRICAL NACA 0012 WITH A PITCHING MOTION BETWEEN AOAS 5 DEG. AND 25 DEG. ABOUT ITS QUARTER-CHORD WITH A SINUSOIDAL MOTION. WE HAVE UTILIZED COMPUTATIONAL FLUID DYNAMICS (CFD) TOOL TO NUMERICALLY DETECT DYNAMIC STALL VORTEX (DSV) ON THE VERGE OF ITS FORMATION. THEN, WE HAVE PLACED THE JET SLOT AT THE SEPARATION POINT UPSTREAM THE DSV AND SOME OTHER LOCATIONS NEARBY TO PERFORM SENSITIVITY ANALYSIS. OUR RESULTS SHOWED THAT PLACING THE JET SLOT WITHIN A VERY SMALL RANGE UPSTREAM THE LOCATION OF SEPARATION POINT HAS TREMENDOUS EFFECTS ON BOTH LIFT AND DRAG, SUCH THAT MAXIMUM DRAG WHICH OCCURS AT MAXIMUM INCIDENCES REDUCED BY 80%. THERE WAS ANOTHER UNIQUE OBSERVATION: PUTTING JET AT SEPARATION POINT LEADS TO AN INVERSE BEHAVIOR OF DRAG HYSTERESIS CURVE IN UPSTROKE AND DOWNSTROKE MOTIONS. DRAG IN DOWNSTROKE MOTION IS SIGNIFICANTLY LOWER THAN UPSTROKE MOTION, WHEREAS IN UNCONTROLLED CASE THE CONVERSE IS TRUE. IN ADDITION, BY IMPLEMENTING JET FLOW LIFT IS SIGNIFICANTLY ENHANCED DURING BOTH UPSTROKE AND DOWNSTROKE MOTIONS. FINALLY, IT SHOULD BE INDICATED THAT THIS STUDY PROVIDES INITIAL STEPS IN INVESTIGATIONS OF APPLYING SYNTHETIC JET ACTUATOR (SJA) ON A PITCHING AIRFOIL AT HIGH REYNOLDS NUMBER 1´106 WITH EFFECTS OF CHANGING MOMENTUM RATIO AND SJA FREQUENCY, WHICH WILL BE PRESENTED IN THE NEAR FUTURE.

THE MIXING EFFECT WAS STUDIED NUMERICALLY BY CALCULATING THE FLOWS DRIVEN BY OSCILLATING STIRRERS IN A MICROCHANNEL. THE EFFECTS OF MOLECULAR DIFFUSION AND DISTURBANCE BY THE STIRRER FOR MIXING WERE EXAMINED. THE MIXING WAS SIMULATED USING THE COMPUTATIONAL FLUID DYNAMICS METHOD BY AN ANSYS CFX. IN THIS STUDY, A TIME-AVERAGED MIXING INDEX WAS USED TO ESTIMATE THE MIXING PERFORMANCE OF A TIME-DEPENDENT FLOW. THE RESULTS REVEALED THAT THE MIXER, USING AN OSCILLATING STIRRER, WAS MUCH MORE ENHANCED AND STABILIZED. THEREFORE, AN OPTIMUM DESIGN FOR AN ACTIVE MICRO-MIXER WITH AN OSCILLATING STIRRER WAS PERFORMED BASED ON THE TAGUCHI METHOD IN ORDER TO OBTAIN A ROBUST SOLUTION. THE DESIGN PARAMETERS WERE SELECTED AS THE REDUCED FREQUENCY, THE LENGTH OF STIRRER AND THE ROTATION ANGLE OF THE STIRRER, AND THE OPTIMAL VALUES WERE DETERMINED AS 0.54, 0.8 AND±60O, RESPECTIVELY. IT WAS FOUND THAT THE MIXING INDEX OF THE OPTIMAL DESIGN WAS IMPROVED BY UP TO 28.46% COMPARED TO THAT OF THE INITIAL DESIGN.

FLOW CONTROLLERS ARE SIMPLE SMALL PARTS INSTALLED NEAR THE MAIN CYLINDERS OR BLUFF BODIES TO REDUCE THE WAKE REGION AND DELAYING THE VORTEX SHEDDING. IN THE PRESENT WORK, NUMERICAL STUDY OF THE UNSTEADY TWO-DIMENSIONAL LAMINAR FLOW AROUND A CIRCULAR CYLINDER, AT THE PRESENCE OF TWO ROTATING CONTROLLERS ON THE VERTICAL CENTERLINE, IS STUDIED. THE FINITE VOLUME METHOD BASED ON SIMPLE SCHEME IS USED. THE EFFECT OF THE ROTATION RATE, THE VERTICAL GAP AND ESPECIALLY THE SIZE OF ROTATING CYLINDERS ARE DISCUSSED. THE ROTATING CYLINDERS SHOULD BE MOUNTED ON A SPECIFIC RANGE OF THE VERTICAL GAP TO EFFECT ON THE NEAR WAKE OF THE MAIN CYLINDER. IT IS FOCUSED ON FINDING THE OPTIMUM CONTROLLER DIAMETER SIZES. IN A SPECIFIC RANGE OF CONTROLLER DIAMETER, THE DOWNSTREAM FLUID IS CHANGED, EFFECTIVELY. COMPARING THE FLOW PASSED A SINGLE CYLINDER AS WELL AS AT THE PRESENCE OF ROTATING CYLINDERS, IN A FIXED LOW REYNOLDS NUMBER, IS PERFORMED. RESULTS SHOW THAT THE MINIMUM AMPLITUDE OF THE LIFT AND DRAG FLUCTUATIONS ARE OBTAINED BY SETTING UP THE DOMINATING PARAMETERS ON THE OPTIMUM RANGES. THE ELIMINATION OF THE TRAVERSE VELOCITIES GENERATES A NARROWER VON-KARMAN STREET. THE VORTEX GENERATION IS DELAYED AND THE FREQUENCY OF SHEDDING IS DECREASED. THE PRESSURE IN FRONT OF THE MAIN CYLINDER IS INTENSIFIED AND THE AMOUNT OF UNSTEADY DRAG COEFFICIENT IS INCREASED AS WELL.

THE INFLUENCE OF TWO-PHASE FLOW PATTERNS ESPECIALLY SLUG AND BUBBLE PATTERNS HAS BEEN INVESTIGATED IN THE RECENT STUDIES OF EFFECT OF GAS INJECTION ON MEMBRANE FOULING. THE CONSEQUENCES DEMONSTRATE THAT SLUG FLOW IS MORE EFFECTIVE THAN BUBBLE FLOW IN TERMS OF ENHANCING SHEAR FORCE AND PERMEATE FLUX. IN THIS PAPER, AN EXPERIMENTAL STUDY IS PERFORMED TO INVESTIGATE THE FOULING REDUCTION IN AN ULTRAFILTRATION PROCESS USING GAS FLOW INJECTION. THE EFFECT OF SLUG AND BUBBLE PATTERNS ON PERMEATE FLUX IN THE ULTRAFILTRATION PROCESS IN A FLAT SHEET MODULE IS ANALYZED WITH A VIDEO SYSTEM FACILITATED WITH A HIGH SPEED CAMERA. THE CHARACTERISTICS OF BUBBLES SUCH AS THEIR DISTRIBUTION AND VELOCITY ARE MEASURED BY IMAGE PROCESSING. THE RESULTS SHOW THAT THE AMOUNTS OF FLUCTUATING AND AVERAGE VELOCITY OF THE SLUG FLOW WERE LARGER THAN THOSE OF THE BUBBLE FLOW. THE HIGHER VELOCITY OF BUBBLES IN THE SLUG FLOW ENHANCES PERMEATE FLUX MORE.

IN THIS PAPER, BUBBLE DYNAMICS IN A ROTATING FLOW WAS STUDIED, APPLYING LATTICE BOLTZMANN METHOD. THE RESULTS WERE VALIDATED WITH THOSE REPORTED BY PREVIOUS RESEARCHERS. COMPARISON OF THE PRESENT STUDY BY PREVIOUS RESEARCH SHOWED GOOD CONSISTENCY. AFTERWARD, FLOW PHYSICS OF THE PROBLEM WAS STUDIED IN DETAIL. IN THIS REGARD, ROTATION, DEFORMATION, AND STRETCHING OF THE BUBBLE WERE DISCUSSED. THE RESULTS SHOWED THAT IN THE ROTATING FLOW THE BUBBLE MOVED TOWARD TO THE CENTER OF THE ROTATION AXIS. DURING THIS MOVEMENT, THE BUBBLE IS COMPRESSED, STRETCHED, DEFORMED AND FINALLY IT WENT TO A STEADY POSITION AT THE ROTATION AXIS. ALSO, BUBBLES WITH DIFFERENT DENSITY RATIOS, 2, 10 AND 50, WERE CONSIDERED AND THEIR PATHLINE WERE COMPARED. IN ANOTHER TEST CASE, BUBBLES PATHLINES WITH DIFFERENT RATIOS OF BUBBLES DIAMETERS TO CAVITY LENGTH, D/L=0.1, 0.13 AND 0.17 WERE STUDIED. THE RESULTS DEMONSTRATED THAT THE BALANCES BETWEEN THE FORCES EXERTED ON THE BUBBLE WOULD DETERMINE THE BUBBLE TRAJECTORY.

NUMERICAL SIMULATIONS HAVE BEEN CARRIED OUT TO INVESTIGATE THE MIXING BEHAVIOR IN THE DIFFERENT SERPENTINE MICRO-CHANNELS WITH NON-NEWTONIAN FLUIDS USING SHEAR-DEPENDENT VISCOSITY MODELS. THE CARREAU-YASUDA AND QUEMADA NON-NEWTONIAN VISCOSITY MODELS HAVE BEEN USED. SINUSOIDAL-SHAPE, STEP-SHAPE AND ZIGZAG-SHAPE HAVE BEEN USED AS THREE DIFFERENT SERPENTINE MODELS. 3-D GOVERNING EQUATIONS, CONTINUITY, MOMENTUM AND SPECIES EQUATIONS HAVE BEEN SOLVED WITH FLUENT SOFTWARE. RESULTS SHOW IN THE SINUSOIDAL-SHAPE, VERY BETTER MIXING ACHIEVED THAN STRAIGHT LENGTH MICRO-CHANNEL FOR BOTH NON-NEWTONIAN MODELS. ALSO, IN THE SINUSOIDAL-SHAPE, BETTER MIXING REPRESENTED THAN ZIGZAG-SHAPE AND MIXING INDEX IN ZIGZAG-SHAPE IS HIGHER THAN STEP-SHAPE. ON THE OTHER HAND, IN ALL THREE MODELS, FIRSTLY WITH INCREASING MASS FLOW RATE, MIXING INDEX DECREASES. BUT FOR MASS FLOW RATE HIGHER THAN ABOUT 2´10-6 KG/S, WITH INCREASING MASS FLOW RATE, MIXING INDEX INCREASES. ALSO, AT LOW MASS FLOW RATE, THERE IS NO DIFFERENCE IN MIXING INDEX FOR CARREAU-YASUDA AND QUEMADA NON-NEWTONIAN VISCOSITY MODELS, BUT WITH INCREASING MASS FLOW RATE, MIXING INDEX FOR CARREAU-YASUDA MODEL IS HIGHER THAN QUEMADA MODEL.

IN THIS PAPER THE EFFECTS OF SUCTION AND INJECTION ON VELOCITY AND CONCENTRATION BOUNDARY LAYER INVESTIGATED. THE STEADY LAMINAR BOUNDARY LAYER FLOW OVER A PERMEABLE FLAT PLATE IN A UNIFORM FREE STREAM IS CONSIDERED THAT THE BOTTOM SURFACE OF THE PLATE IS SUBJECTED TO THE MASS TRANSFER BY CONVECTION FROM A HOT FLUID. CONTINUITY, MOMENTUM AND CONCENTRATION EQUATIONS ARE WRITTEN AND BECOME A NON-DIMENSIONAL FORM FINALLY. SIMILARITY SOLUTIONS FOR THE FLOW AND CONCENTRATION FIELDS ARE POSSIBLE IF THE MASS TRANSPIRATION RATE AT THE SURFACE AND THE CONVECTIVE HEAT TRANSFER FROM THE HOT FLUID ON THE LOWER SURFACE OF THE PLATE VARY LIKE X½ WHERE X IS THE DISTANCE FROM THE LEADING EDGE OF THE SOLID SURFACE. IN THIS PROCESS, PARTIAL DIFFERENTIAL EQUATIONS ARE CONVERTED INTO ORDINARY DIFFERENTIAL EQUATIONS AND SOLVED WITH RUNGEKUTTA METHOD. EFFECT OF VARIOUS PARAMETERS ON THE MASS TRANSFER AND BOUNDARY LAYER THICKNESS AND FLOW ARE REVIEWED AND DISCUSSED.

EFFICIENT OPERATION OF PROTON EXCHANGE MEMBRANE FUEL CELL (PEMFC) IS CRITICALLY ASSOCIATED TO EFFECTIVE COOLING SYSTEM. NON-UNIFORMITY OF TEMPERATURE CAUSES THE RATE OF ELECTROCHEMICAL REACTION AT DIFFERENT PLACE WILL BE VARYING. ACCORDING TO THIS ISSUE HOT SPOT WILL ACCRUED AND THE LIFETIME OF PEM FUEL CELL WILL DECREASE. THE MOST PART OF HEAT GENERATION IN THE PEM FUEL CELL REMOVE USING COOLING FLUID AND A LITTLE PART REMOVE BY NATURAL CONVECTION, RADIATION AND TEMPERATURE DIFFERENCE BETWEEN INLET AND OUTLET OF REACTION GASES. WHEREOF THE REACTION RATE AND CURRENT DENSITY IS RELATED TO TEMPERATURE THEREFORE THE TEMPERATURE DISTRIBUTION SHOULD BE UNIFORM AT THE SURFACE OF ACTIVE AREA FOR ACHIEVEMENT OF UNIFORM CURRENT DENSITY. IN THIS EFFORT, NEW COOLING FLOW FIELDS ARE NUMERICALLY INVESTIGATED IN ORDER TO CLARIFY THE SUFFICIENT DESIGN FOR THE HEAT REMOVAL. NUMERICAL SIMULATION IS APPLIED TO INVESTIGATE THE COOLANT FLOW DISTRIBUTION, PRESSURE DROP AND THERMAL BEHAVIOR OF DIFFERENT DESIGNS. THE TEMPERATURE CONTOURS REPRESENT THE TEMPERATURE UNIFORMITY FOR THE ASSESSED CASE.

IN THIS NUMERICAL STUDY, EXERGY ANALYSIS OF A RANQUE-HILSCH VORTEX TUBE HAS BEEN INVESTIGATED. THE THREE-DIMENSIONAL (3D) COMPUTATIONAL FLUID DYNAMIC (CFD) MODEL WHICH IS USED IN THIS STUDY IS A STEADY AXISYMMETRIC MODEL THAT EMPLOYS TWO TURBULENCE MODELS (STANDARD K-E AND STANDARD K-W) TO PERFORM THE COMPUTATION PROCEDURE OF RESULTS. THE CURVES OF ENERGY PERFORMANCE SUCH AS INLET ENERGY, ENERGY OF COLD AND HOT OUTLET, LOST ENERGY AND ENERGY EFFICIENCY HAVE BEEN ACHIEVED FOR THE PRESENT VORTEX TUBE. THESE CURVES HAVE BEEN VALIDATED WITH THE EXPERIMENTAL DATA AND HAVE SHOWN GOOD AGREEMENT. IN THIS PAPER, VARIATION OF ENERGY IN THE COLD AND HOT EXIT HAS BEEN PREDICTED AS A FUNCTION OF COLD MASS FRACTION AND THE BEHAVIORS OF OBTAINED CURVES HAVE BEEN DISCUSSED. IN ADDITION, VARIATION OF TEMPERATURE AND PRESSURE IN THE COLD AND HOT EXHAUST HAS BEEN PRESENTED AS A FUNCTION OF COLD MASS FRACTION. THE RESULTS SHOW THAT THE LOST ENERGY IS MAXIMAL WHEN THE PRESSURE OF OUTLETS REACHES TO MINIMUM VALUE. THE MAXIMUM ENERGY EFFICIENCY OF THIS CASE OCCURS IN A COLD MASS FRACTION OF 0.21 THAT IS APPROVED BY THE EXPERIMENTAL RESULTS.

IN THIS STUDY, THE DYNAMIC AND PARAMETRIC INSTABILITIES OF A PINNED–PINNED SINGLE-WALLED CARBON NANOTUBE (SWCNT) CONVEYING FLUID WITH NON-UNIFORM FLOW VELOCITY ARE MODELED AND NUMERICALLY INVESTIGATED. THE PARTIAL DIFFERENTIAL EQUATION OF MOTION IS DERIVED BASED ON THE NONLOCAL ELASTICITY THEORY, EULER-BERNOULLI BEAM THEORY AND FLUID–TUBE INTERACTION. ALSO, THE MOMENTUM CORRECTION FACTOR IS DERIVED FOR NANO-FLOW AS FUNCTION OF THE KNUDSEN NUMBER. THEN, BASED ON THE GALERKIN WEIGHTED RESIDUAL METHOD, COMPLEX EIGEN-FREQUENCIES ARE INVESTIGATED WITH RESPECT TO FLOW VELOCITY AS WELL AS OTHER CONSIDERED PHYSICAL PARAMETERS. FURTHERMORE, THE INFLUENCES OF SLIP BOUNDARY CONDITION AND NON-UNIFORM FLOW VELOCITY ON THE DYNAMIC BEHAVIOR OF THE CNT-FLUID SYSTEM ARE ANALYZED. FINALLY, IT IS CONCLUDED THAT NON-UNIFORMITY INFLUENCE OF FLOW VELOCITY ON THE STABILITY OF CNT, IS FUNCTION OF THE KNUDSEN NUMBER AND SMALL-SIZE OF THE NANO-FLOW, SO THAT IGNORING THEIR EFFECTS IN VIBRATIONAL ANALYSES OF CNT CONVEYING FLUID MAY CAUSE ERRONEOUS RESULTS.

A DOUBLE-GPU CODE IS DEVELOPED TO SIMULATE COMPRESSIBLE VISCOUS EQUATIONS. THE CODE WRITTEN IN CUDA PROGRAMMING LANGUAGE IS DEVELOPED BY MODIFYING A SINGLE-GPU CODE. THE OPENMP LIBRARY IS USED FOR PARALLEL EXECUTION OF THE CODE ON BOTH THE GPUS. DATA TRANSFER BETWEEN GPUS WHICH IS THE MAIN ISSUE IN DEVELOPING THE CODE, IS CARRIED OUT BY DEFINING HALO POINTS FOR NUMERICAL GRIDS AND ALSO BY USING CUDA BUILT-IN FUNCTIONS.

VIBRATION AND INSTABILITY OF SINGLE-WALLED CARBON NANOTUBES (SWCNTS) CONVEYING FLUID ARE INVESTIGATED IN THIS PAPER BY CONSIDERING NON-UNIFORMITY INFLUENCES OF FLOW VELOCITY CAUSED BY SLIP BOUNDARY CONDITION AND VISCOSITY OF FLUID. IN ADDITION, THE MODIFIED COUPLE STRESS THEORY AND THE EULER-BERNOULLI BEAM THEORY ARE EMPLOYED IN ORDER TO MODEL CNT AND TAKE THE SIZE EFFECTS INTO ACCOUNT. FURTHERMORE, SLIP BOUNDARY CONDITION ATTRIBUTABLE TO NANO-FLOW EFFECTS IS CONSIDERED. THE GALERKIN WEIGHTED RESIDUAL METHOD IS UTILIZED TO DISCRETIZE THE GOVERNING EQUATIONS, WHICH ARE THEN SOLVED TO OBTAIN THE RESONANT FREQUENCIES OF FLUID-CONVEYING SWCNTS WITH SIMPLY SUPPORTED BOUNDARY CONDITION. FINALLY, IT IS CONCLUDED THAT CNTS CONVEYING FLUID FLOW WITH NON-UNIFORM VELOCITY PROFILE ARE MORE UNSTABLE RATHER THAN CNTS CONVEYING PLUG FLOW.

IN THIS PAPER, THE ELECTRO HYDRODYNAMIC (EHD) RESPONSES OF A DEFORMABLE FLUID DROP IN ANOTHER IMMISCIBLE FLUID UNDER THE ACTION OF A UNIFORM ELECTRIC FIELD IS INVESTIGATED. DROP AND IMMISCIBLE FLUID, ARE CONSIDERED PERFECT CONDUCTIVE AND INSULATING, RESPECTIVELY. WHEN A DROP IS SUBJECTED TO AN ELECTRIC FIELD DUE TO THE PHYSICAL PROPERTIES AND THE INDUCED ELECTRIC FIELD, DIFFERENT DYNAMIC BEHAVIOR MAY BE OBSERVED. AN ACCURATE NUMERICAL METHOD IS REQUIRED TO CAPTURE THESE DEFORMATIONS. FOR THIS PURPOSE, THE LEVEL SET METHOD IS USED ALONG WITH THE GHOST FLUID METHOD FOR TRACKING THE INTERFACE AND APPLYING DISCONTINUITIES ACROSS THE INTERFACES, RESPECTIVELY. THE INCOMPRESSIBLE NAVIER-STOKES EQUATION IS EMPLOYED TO MODEL THE INTERNAL AND EXTERNAL FLUID FLOW OF THE DROPLET. MAXWELL'S EQUATIONS ARE USED TO SOLVE THE ELECTRIC FIELD. THE RESULTS OF THE SIMULATIONS ARE COMPARED WITH AVAILABLE SIMILAR NUMERICAL AND EXPERIMENTAL RESULTS. THE SIMULATION RESULTS CONFIRM THE ACCURACY OF THE METHOD.

IN THIS STUDY, A CFD SIMULATION IS USED TO INVESTIGATE THE EFFECT OF ADDING DIFFERENT NANO PARTICLES TO THE FLUID ON THE PERFORMANCE OF SHELL AND TUBE HEAT EXCHANGER WITH BAFFLES. NANO PARTICLES ADDITION WILL CHANGE THE THERMO-PHYSICAL PROPERTIES. THIS CAN BE LEADS TO INCREASING OR DECREASING THE HEAT TRANSFER COEFFICIENT DEPENDING ON THE FLUID FLOW. IN THE PRESENT STUDY, A THREE-DIMENSIONAL MODELING IS USED TO INVESTIGATE THE EFFECT OF DIFFERENT NANO FLUIDS WITH VARY VOLUME FRACTIONS FOR APPLICATION IN BAFFLED SHELL AND TUBE HEAT EXCHANGER. AFTER GRID INDEPENDENCY AND RESULTS VALIDATION, THE RATE OF HEAT TRANSFER, PRESSURE DROP AND OUTLET SHELL TEMPERATURE ARE OBTAINED FOR DIFFERENT VOLUME FRACTION OF ALL NANO FLUIDS. NANO PARTICLES WHICH ARE USED IN THE PRESENT WORK ARE CONSISTED OF AL2O3, CUO, FE2O3, CU, FE AND AU WITH WATER AS BASE FLUID. THE RESULTS INDICATE THAT THE ADDITION OF NANO PARTICLES REDUCES THE HEAT TRANSFER COEFFICIENT, PRESSURE DROP AND SHELL HEAT TRANSFER RATE BUT LEADS TO INCREASING IN OUTLET SHELL TEMPERATURE. IN OTHER WORDS, CONSIDERING A CONSTANT HEAT TRANSFER RATE, USING SOME NANO-FLUIDS IN BAFFLED SHELL AND TUBE HEAT EXCHANGER WILL INCREASE THE OUTLET TEMPERATURE OF THE SHELL.

PLANAR LASER INDUCED FLUORESCENCE HAS BEEN INTRODUCED AS A METHOD OF STUDYING WATER DROP IMPACTING DEEP WATER POOL, SPECIFICALLY THE PENETRATION A DROP AFTER COLLISION. THE GENERAL FORMULATION AND LAW BEHIND THE PLIF METHOD WAS FORMULATED. THEN, THE EXPERIMENTAL SETUP IS DESCRIBED. FINALLY, TWO SERIES OF IMAGES TAKEN FROM DROPS WITH DIFFERENT IMPACT SPEEDS (WEBER NUMBERS) ARE SHOWN AND THE DATA THAT CAN BE EXTRACTED FROM THEM ARE ILLUSTRATED. THE PHOTOS SHOW THE VORTEX RING PRODUCED BY DROP IMPACT AT LOW IMPACT SPEEDS. THIS RING WILL CAUSE TO PENETRATE FASTER AND DEEPER THAN HIGHER IMPACT VELOCITIES WITHOUT MENTIONED VORTEX RING.

IN THIS PAPER, AN ITERATIVE PHYSICAL-BASED INVERSE METHOD NAMED BALL SPINE ALGORITHM (BSA) IS DEVELOPED FOR SOLVING INVERSE HEAT CONDUCTION PROBLEMS. SHAPE OPTIMIZATION FIELD OF STUDY REFERS TO SPECIAL PROBLEMS IN WHICH RESEARCHERS ARE INTERESTED IN DESIGNING CONFIGURATION OF THE BODY SUCH THAT ITS SURFACE SATISFIES A PRESCRIBED FUNCTION. THE INVERSE PROBLEM IS DESCRIBED AS A HEAT SOURCE EMBEDDED WITHIN A SOLID MEDIUM WITH KNOWN TEMPERATURE DISTRIBUTION. THE OBJECT IS FINDING A BODY CONFIGURATION SATISFYING A PRESCRIBED HEAT FLUX ORIGINATED FROM A HEAT SOURCE ALONG THE OUTER SURFACE OF THE BODY. RESULTS SHOW THAT THE PROPOSED METHOD IS SO ROBUST AND IT HAS A TRULY LOW COMPUTATIONAL COST ACCOMPANIED WITH HIGH CONVERGENCE RATE.

THE GAS-SOLID FLOW BEHAVIOR OF A CONICAL SPOUTED BED INCLUDING HEAVY PARTICLES WITH DENSITY OF R=6050 KG/M3 THAT TYPICALLY ENCOUNTERED IN CHEMICAL VAPOR DEPOSITION (CVD) WAS STUDIED BY THE CFD TECHNIQUE. AN EULERIAN-EULERIAN TWO-FLUID MODEL (TFM) IN CONJUNCTION WITH THE KINETIC THEORY OF GRANULAR FLOWS (KTGF) WAS USED IN A FULL 3D COMPUTATIONAL FRAMEWORK. TO REDUCE THE COMPUTATIONAL TIME WHILE MAINTAINING THE ACCURACY OF THE RESULTS, POLYHEDRAL MESH STRUCTURE WAS UTILIZED. THE HYDRODYNAMICS PARAMETERS INCLUDING PARTICLE VELOCITY AND SOLID VOLUME FRACTION PROFILES AT DIFFERENT BED LEVELS WERE EVALUATED, AND THE OVERALL BEHAVIOR OF PARTICLES IN THE BED WAS STUDIED. IT WAS SHOWN THAT THE CFD RESULTS AGREE WELL WITH THE EXPERIMENTAL MEASUREMENTS. INCOHERENT SPOUTING WAS ALSO PROPERLY PREDICTED BY THE MODEL, AND WAS SHOWN TO BE IN ACCORDANCE WITH THE EXPERIMENTAL OBSERVATIONS.

IN THIS STUDY, THE NON-NEWTONIAN FLUID FLOW THROUGH THE 2D CHANNEL WITH BACK-WARD FACING STEP AND BAFFLE WAS INVESTIGATED NUMERICALLY. THE EFFECTS OF POWER-LAW INDEX, BAFFLE HEIGHT AND DISTANCE OF BAFFLE FROM THE STEP ON ENTROPY GENERATION, HEAT TRANSFER AND HYDRODYNAMIC CHARACTERISTICS WERE STUDIED. THE POWER-LAW MODEL WAS USED FOR SIMULATION THE NON-NEWTONIAN FLUID. AS WELL, THE FLOW ASSUMED STEADY, INCOMPRESSIBLE AND LAMINAR. IN THIS STUDY THE PRANDTLE NUMBER AND THE REYNOLDS NUMBER WERE CONSTANT FOR ALL CASES, AND EQUAL TO 0.71 AND 400, RESPECTIVELY. THE RESULTS SHOWED THAT THE ENTROPY GENERATION NUMBER INCREASES AND BEJAN NUMBER DECREASES BY INCREASING THE POWER-LAW INDEX. ALSO, EXISTENCE OF BAFFLE SHOWED SIGNIFICANT EFFECT ON ENTROPY GENERATION, NUSSELT NUMBER AND FRICTION COEFFICIENT AS, THE MAXIMUM VALUES OF THESE PARAMETERS ON BOTTOM WALL TAKE PLACE JUST BELOW THE BAFFLE. BESIDES, THE RESULTS SHOW THAT FOR CERTAIN GEOMETRY, THE MAXIMUM VALUES OF NS, NU AND CF MOVE TOWARD THE STEP AS POWER-LAW INDEX INCREASES.

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