THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Development of a multicriteria tool for optimizing the renovation of buildings

Marine propellers and propulsion

Chaotic advection plays an important role in microplatforms for a variety of applications. Currently used mechanisms for inducing chaotic advection in small scale, however, are limited by their complicated fabrication processes and relatively high power consumption. Here, a soft actuator is reported which utilizes a droplet of Galinstan liquid metal to induce harmonic Marangoni fl ow at the surface of liquid metal when activated by a sinusoidal signal. This liquid metal actuator has no rigid parts and employs continuous electrowetting effect to induce chaotic advection with exceptionally low power consumption. The theory behind the operation of this actuator is developed and validated via a series of experiments. The presented actuator can be readily integrated into other microfl uidic components for a wide range of applications.

Liquid Metal Actuator for Inducing Chaotic Advection

Plate heat exchangers have been widely applied in numerous industrial applications since their first commercial exploitation in the 1920s. Enhancing the thermal-hydraulic performance of plate heat exchangers is of crucial importance for the energy conversion as well as for the improvement of the system economy, through savings in the capital investment. The efficiency of a plate heat exchanger can be improved either by optimizing its geometry or using heat transfer enhancement techniques. This paper provides a comprehensive review of previous works regarding the effects of chevron corrugation geometrical parameters on the performance of plate heat exchangers, and the application of heat transfer enhancement techniques in plate heat exchangers, focusing on passive surface techniques and the use of nanofluids. The objective of the paper is not only to describe relevant studies, but also to provide an understanding of the heat transfer mechanisms governing the results, and to evaluate and compare the different heat transfer enhancement techniques. In addition, prospective directions for future research are provided. The review indicates that for the chevron-type plate heat exchanger, the chevron angle is the most influential geometrical parameter by changing the flow structures in the single-phase heat transfer; meanwhile the chevron angle has a significant influence on the heat transfer regions characterized by convection in the two-phase heat transfer. An analysis based on the performance evaluation criteria suggests that the thermal-hydraulic performances of the studies with different geometrical parameters and enhancement techniques are generally higher at low Reynold numbers. Furthermore, the review and analysis indicate that the capsule-type embossing surface and the microstructured surface with a nano- and microporous layer are the enhancement techniques that present the highest performance in single-phase and two-phase heat transfer, respectively.

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A review of heat transfer enhancement techniques in plate heat exchangers

Numerical simulation of the plug and the slug flow regimes have been performed using the Multi-Fluid VoF and Shear Stress Transport (SST) k–ω models in a horizontal pipe with 44 mm diameter. The superficial velocities during the current study were set at 0.16, 1.64 & 3 m/s for the gas phase and 1 m/s for the liquid one. The pressure and the velocity equations were solved together, utilizing the PIMPLE algorithm in all cases of the present study. The VoF model, as well as the experimental outcomes, were applied to assess the results of Multi-Fluid VoF model. The qualitative comparison of numerical results with the experimental visualization revealed that the Multi-Fluid VoF model simulates precisely the interfacial structure of slug and plug flows, as well as the chronological formation of the slug. The length ratio of the gas slug to the liquid slug goes up with the gas superficial velocity increment; this issue increases the probability at low liquid hold-ups and decreases the higher ones. The Multi-Fluid VoF provided much more matching with the mentioned probability changes in comparison to the VoF model. The pressure drop calculated using Multi-Fluid VoF in the Lockhart–Martinelli framework illustrated a 21.8% improvement averagely in comparison to the VoF model. The obtained transitional slug velocities showed that the Multi-Fluid VoF model presented a maximum error of 8.17% versus the experimental values, while the mentioned error for the VoF model was estimated at 22.01%. Notwithstanding the mentioned advantages, the Multi-Fluid VoF model significantly increased, both the execution time of simulation as well as the associated costs.

Multi-Fluid VoF model assessment to simulate the horizontal air–water intermittent flow

This paper aims to study the drag reduction of a superhydrophobic nanocomposite coating for engineering applications. In the method developed, a suspension of hydrophobic silica nanoparticles in PDMS/toluene solution was prepared. Then a spray-deposition method is used to deposit a layer of nanocomposite composed of PDMS/hydrophobic silica nanoparticles on the surface. After curing the samples at 100 °C for 1 h the nanocomposite coating was prepared. The surface morphology of the coating was characterized by scanning electron microscopy and static water contact angle measurement. The superhydrophobic properties of fabricated surfaces are investigated through different PDMS/hydrophobic silica nanoparticles ratios. It was found that the presented nanocomposite coating method was an effective technology which was suitable to form large-area superhydrophobic coating with a water droplet (5 μL) roll-off angle of less than 5°. The hydrostatic pressure test showed that the Cassie−Baxter state of the fabricated coating is stable in front of the applied pressure up to 50 kPa. Drag reduction tests showed that the air-layer placed at the water-superhydrophobic interface was stable in front of wall shear stress up to 11 Pa. The maximum drag reduction and slip length were measured about 25% and 70 μm, respectively.

Slip length measurement of pdms/hydrophobic silica superhydrophobic coating for drag reduction application

In this paper, the ventilated supercavities are studied both numerically and experimen-tally. A slender rod is considered as the solid body which has a sharp edged disk at thenose as a cavitator and special ports for air ventilation. The experiments are conductedin a recirculating water tunnel. The simulations are provided for two different algorithmsin free-surface treatment, both using the VOF method but one using Youngs’ algorithm inthe advection of the free-surface and the other without. The comparison between numeri-cal simulations and experiments show that the numerical method using Youngs’ algo-rithm accurately simulates the physics of ventilated cavitation phenomena such as thecavity shape, the gas leakage and the re-entrant jet. [DOI: 10.1115/1.4027383]Keywords: ventilated cavitation, numerical, water tunnel, volume of ﬂuid, Youngs’method

/pdf/numerical-and-experimental-study-of-a-ventilated-3yupjlexyz.pdf

Numerical and Experimental Study of a Ventilated Supercavitating Vehicle

The role of autonomous underwater vehicles (AUVs) is more important in the quest to reach the deep seas today than ever before. The hull shape of the AUV can differ depending on the special mission considered for the vehicle. Therefore, different types of algorithms for the body shape design of these kinds of vehicles are being developed every day. In the current work, a new procedure has been proposed for designing the body shape of an AUV. Using this method which is based on a desired pressure distribution, it is possible to obtain the desired hull shape design. Artificial neural network algorithm has been used for this purpose. Preliminary data for training and testing of the network have been obtained from CFD simulation of the flow around the body of Hydrolab500 AUV. In this regard, pressure distribution has been evaluated around each body by changing the nose and tail profile of AUV. The results obtained from this research indicate that a body correlated to the desired pressure can be designed properly.

AUV hull shape design based on desired pressure distribution

This paper investigates a theoretical prediction of friction drag reduction in turbulent channel flow which is achieved by using superhydrophobic surfaces. The effect of the hydrophobic surface is considered to be a slip boundary condition on the wall, and this new boundary condition is added to Large Eddy Simulation (LES) equations. The predicted drag reduction at Re
 τ
 = 180 is approximately 30%, which concurs with results obtained from Direct Numerical Simulation (DNS). An important implication of the present finding is that the near-wall turbulence structures are modified with streamwise slip velocity. In addition, a noticeable effect on the turbulence structure occurs when the slip length is greater than a certain value.

Nowrouz Mohammad Nouri

Papers

Multi-Fluid VoF model assessment to simulate the horizontal air–water intermittent flow

Slip length measurement of pdms/hydrophobic silica superhydrophobic coating for drag reduction application

Numerical and Experimental Study of a Ventilated Supercavitating Vehicle

AUV hull shape design based on desired pressure distribution

Drag Reduction in a Turbulent Channel Flow with Hydrophobic Wall