scholarly journals Calm Water Performance of Hard-Chine Vessels in Semi-Planing and Planing Regimes

2016 ◽  
Vol 23 (4) ◽  
pp. 23-45 ◽  
Author(s):  
Parviz Ghadimi ◽  
Sasan Tavakoli ◽  
Abbas Dashtimanesh
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Iterative Method ◽  
Performance Prediction ◽  
Equilibrium Equations ◽  
Frictional Drag ◽  
Pressure Distributions ◽  
Induced Drag ◽  
Proposed Model ◽  
Calm Water

Abstract In the current paper, a mathematical model is developed for performance prediction of hard-chin boats which can be used in both semi-planing and planing regimes. The proposed model bases on the 2D+T theory and implements pressure distributions over the length of the hull in order to compute the forces. To determine the forces in the semi-planing range, a function is proposed for the non-dimensional length at which the transom effect appears. Three drag components, which are: frictional drag, induced drag, and spray drag, are considered in the computations performed using an iterative method to satisfy two equilibrium equations. The validity of the proposed method is verified by comparing the predicted trim angle and resistance against the available experimental data. Based on this comparison, it is observed that the proposed method reveals satisfying accuracy in both semi-planing and planing regimes. The method is then used to study variation of hydrodynamic and hydrostatic forces as the hull makes a transition from the semi-planing regime to the planing regime. In addition, different components of the resistance are analyzed.

Development of a Mathematical Model for Performance Prediction of Planing Catamaran in Calm Water

2019 ◽  
Vol 161 (A2) ◽  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Performance Prediction ◽  
Data Evaluation ◽  
Empirical Equations ◽  
Calm Water ◽  
Semi Empirical ◽  
The Mathematical Model ◽  
Comparison With Experimental Data

In this paper, an attempt has been made to predict the performance of a planing catamaran using a mathematical model. Catamarans subjected to a common hydrodynamic lift, have an extra lift between the two asymmetric half bodies. In order to develop a mathematical model for performance prediction of planing catamarans, existing formulas for hydrodynamic lift calculation must be modified. Existing empirical and semi-empirical equations in the literature have been implemented and compared against available experimental data. Evaluation of lift in comparison with experimental data has been documented. Parameters influencing the interaction between demi-hulls and separation effects have been analyzed. The mathematical model for planing catamarans has been developed based on Savitsky’s method and results have been compared against experimental data. Finally, the effects of variation in hull geometry such as deadrise angle and distance between two half bodies on equilibrium trim angle, resistance and wetted surface have been examined.

DEVELOPMENT OF A MATHEMATICAL MODEL FOR PERFORMANCE PREDICTION OF PLANING CATAMARAN IN CALM WATER

2021 ◽  
Vol 161 (A2) ◽  
Author(s):  
A Ghassemzadeh ◽  
A Dashtimanesh ◽  
M Habibiasl ◽  
P Sahoo
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Performance Prediction ◽  
Data Evaluation ◽  
Empirical Equations ◽  
Calm Water ◽  
Semi Empirical ◽  
The Mathematical Model ◽  
Comparison With Experimental Data

In this paper, an attempt has been made to predict the performance of a planing catamaran using a mathematical model. Catamarans subjected to a common hydrodynamic lift, have an extra lift between the two asymmetric half bodies. In order to develop a mathematical model for performance prediction of planing catamarans, existing formulas for hydrodynamic lift calculation must be modified. Existing empirical and semi-empirical equations in the literature have been implemented and compared against available experimental data. Evaluation of lift in comparison with experimental data has been documented. Parameters influencing the interaction between demi-hulls and separation effects have been analyzed. The mathematical model for planing catamarans has been developed based on Savitsky’s method and results have been compared against experimental data. Finally, the effects of variation in hull geometry such as deadrise angle and distance between two half bodies on equilibrium trim angle, resistance and wetted surface have been examined.

scholarly journals Shubnikov–de Haas Oscillations in Semiconductors at the Microwave-Radiation Absorption

2019 ◽  
Vol 2019 ◽  
pp. 1-5
Author(s):  
G. Gulyamov ◽  
U. I. Erkaboev ◽  
A. G. Gulyamov
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Electromagnetic Field ◽  
Microwave Radiation ◽  
Three Dimensional ◽  
Radiation Absorption ◽  
Narrow Gap ◽  
Proposed Model ◽  
Different Temperatures ◽  
Shubnikov De Haas Oscillations

Mathematical models for the Shubnikov-de Haas oscillations in semiconductors are obtained at the microwave-radiation absorption and its temperature dependence. Three-dimensional image of microwave magnetoabsorption oscillations in narrow-gap semiconductors is established. Using a mathematical model, the oscillations of the microwave magnetoabsorption are considered for different values of the electromagnetic field. The results of calculations are compared with experimental data. The proposed model explains the experimental results in HgSe at different temperatures.

Steady performance prediction of a heeled planing boat in calm water using asymmetric 2D+T model

2016 ◽  
Vol 231 (1) ◽  
pp. 234-257 ◽  
Author(s):  
Parviz Ghadimi ◽  
Sasan Tavakoli ◽  
Abbas Dashtimanesh ◽  
Rahim Zamanian
Keyword(s):  
Performance Prediction ◽  
Computational Algorithm ◽  
Hydrodynamic Force ◽  
Center Of Gravity ◽  
Drag Forces ◽  
Proposed Model ◽  
Hydrostatic Force ◽  
Calm Water ◽  
Pressure Area ◽  
Heeling Moment

This article presents a simple mathematical model for predicting the running attitude of warped planing boats fixed in a heel angle and free to trim and sinkage. The proposed model is based on asymmetric 2D+T theory utilizing a pressure equation which is previously introduced in the literature to compute the hydrodynamic force acting on a heeled planing hull. Integration of pressure distribution on the asymmetric wedge sections enables the suggested model to compute trim angle, center of gravity rise, resistance, and heeling moment acting on the heeled planing boat in calm water. The hydrostatic force in addition to two drag forces acting on the pressure area and spray area are also taken into account. Finally, a computational algorithm is introduced to find the running attitude of the heeled planing boats. The validity of the proposed model is examined by comparing the obtained running attitudes for two planing hulls series with zero heel angle and computed lift force and heeling moment of a heeled planing boat against available experimental data. Based on the comparisons, favorable accuracy is observed for both symmetrical and asymmetrical conditions. Moreover, it is shown that existence of a heel angle can lead to a decrease in trim angle and resistance, while it intensifies the center of gravity rise of planing boats. It is also observed that as the beam Froude number increases, the heeling moment of the heeled boat reduces.

scholarly journals Mathematical Model of Kinetics of Antigens Accumulation in the Process of Periodical Submerged Cultivation of Vibrio cholerae 569В Inaba with Limitation as Regards Carbonic Substrate

2014 ◽  
pp. 96-99
Author(s):  
A. V. Komissarov ◽  
A. K. Nikiforov ◽  
S. N. Zadokhin ◽  
S. A. Eremin ◽  
O. A. Volokh ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Model Comparison ◽  
Initial Conditions ◽  
Accumulation Rate ◽  
Submerged Cultivation ◽  
Maximum Output ◽  
Proposed Model ◽  
Cultivation Process ◽  
Kinetics Of

Presented is mathematical model of kinetics of the process of O-antigen and cholera toxin synthesis during periodical submerged cultivation of V. cholerae 569В Inaba with limitation as regards carbonic substrate. The proposed model is based upon analysis of experimental data on V. cholerae 569В Inaba biomass and antigens accumulation, rate of growth and antigens release, and glucose utilization. Using Mathcad 15.0 software calculated are coefficients of differential equations entering into the mathematical model. Comparison of predicted and experimental data demonstrates that relative error of determination of concentrations of the synthesized substances, glucose and cholera vibrio is between 5 and 20 %. The proposed model permits to determine maximum output of final products and specify the parameters of cultivation process performance at different initial conditions.

scholarly journals Mathematical Model Describes Treatment of Waste Water Using Modified Activated Carbon

2017 ◽  
Vol 14 (1) ◽  
pp. 94 ◽  
Author(s):  
A.S. Ibrahim ◽  
A.S. AL Buloshi ◽  
S.S. AL Zaabi ◽  
L.A. AL Yafai
Keyword(s):  
Waste Water ◽  
Experimental Data ◽  
Mathematical Model ◽  
Activated Carbon ◽  
Active Carbon ◽  
High Accuracy ◽  
Modified Activated Carbon ◽  
Adsorption And Desorption ◽  
Pollutant Concentrations ◽  
Proposed Model

The proposed mathematical model covered in this paper includes the most important parameters associated with the rates of adsorption and desorption. Also, partial pressure is included since it is an important factor that affects rates of adsorption and desorption. The study focuses on the effects of the constant rates on adsorption of pollutant concentrations for benzene, nickel, cadmium, and copper using modified active carbon. When the rate constant of adsorption decreases, the pollutant concentration will also decrease, yielding high acceptable evidence of the logic of the proposed mathematical model. Also, the proposed model is compared with experimental data and other models to give good outcomes with high accuracy. 

Development of a 2D+T theory for performance prediction of double-stepped planing hulls in calm water

2018 ◽  
Vol 233 (3) ◽  
pp. 886-904 ◽  
Author(s):  
Rasul Niazmand Bilandi ◽  
Abbas Dashtimanesh ◽  
Sasan Tavakoli
Keyword(s):  
Mathematical Model ◽  
Performance Prediction ◽  
Empirical Models ◽  
Two Dimensional ◽  
Reasonable Accuracy ◽  
Future Studies ◽  
Normal Forces ◽  
Calm Water ◽  
The Mean ◽  
The Mathematical Model

In this article, a mathematical model based on the 2D+T theory has been developed to predict the performance of two-stepped planing hulls in calm water. It has been attempted to develop a mathematical model without using regression formulas. It leads to development of a computational model with no common limitations related to empirical models which have an individual range of applicability. For this purpose, theoretical solution of water entry of a two-dimensional wedge section has been implemented to compute the pressure distribution over wedge section entering water, and then normal forces acting on the two-dimensional sections are computed. Bottom of the boat has been divided into three different planing surfaces including fore, middle and aft bodies. Computations are performed for each of these surfaces. By integrating the two-dimensional sectional normal forces over the entire wetted length of the vessel, the trim angle, wetted surface and resistance have been obtained. To evaluate the accuracy of the presented method, the obtained results are compared against experimental data and a previous empirical-based method developed by authors. The comparison suggests that the proposed method predicted dynamic trim angle, wetted surface and resistance of double stepped boats with reasonable accuracy. The mean errors in prediction of trim angle, wetted surface and resistance are, respectively, 13%, 16% and 8%. It should also be noted that although computation of running attitudes and resistance of double-stepped planing boats are targeted in this article, the mathematical model has been developed in such a way that it has the potential to model transverse and vertical motions of two-stepped planing hulls in future studies.

Effect of Spray-Strake on Patrol Vessel Manoeuvrability

2008 ◽  
Author(s):  
Andi Haris Muhammad ◽  
Adi Maimun ◽  
Omar Yaakob ◽  
Agoes Priyanto
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Design Method ◽  
Towing Tank ◽  
Water Condition ◽  
Calm Water ◽  
Planing Vessel

This paper describes a design method on the spray-strake parameters of a planing hull (patrol vessel) based on manoeuvring performance in calm water condition. The method set a spray-strake mathematical model which has been developed using experimental data from towing tank. The model selects such a spray-strake parameter which has the effects on manoeuvrability characteristics. In showing these effects, some IMO manoeuvring (for turning circle and zigzag manoeuvre) have been simulated for a planing hull with the designated spray-strake parameter. The results indicate that the spray-strakes attached to the planing vessel have effects on its manoeuvring performance.

Mathematical Modelling of Heat Transfer in Mortadella Bologna PGI during Evaporative Pre-Cooling

2014 ◽  
Vol 10 (2) ◽  
pp. 233-241 ◽  
Author(s):  
Massimiliano Rinaldi ◽  
Emma Chiavaro ◽  
Roberto Massini
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Heat Transfer Coefficient ◽  
Thermal Diffusivity ◽  
Cooling Process ◽  
Continuous Film ◽  
Cooking Process ◽  
Proposed Model ◽  
Product Surface

Abstract Mortadella evaporative pre-cooling process from 70 to 50°C at core was investigated: the thermal diffusivity and the apparent heat transfer coefficient were experimentally estimated. The effects of ventilation and water spraying with different intervals (0, 5, 10 and 15 min) were tested and core and surface temperatures, cooling times and cook values were compared. Water spraying every 5 min combined with ventilation allowed obtaining both lowest cooling time and cook values in the product. On the contrary, continuous spraying (no interval) presented higher cooling times since probably, after a certain time, water formed a continuous film on product surface, which prevented evaporation. Based on the experimental data, a finite differences mathematical model, previously applied to Mortadella cooking process, was developed and validated by means of two cooling procedures. Acceptable approximation and low percentage errors on final core temperature were obtained, confirming the usefulness and reliability of the proposed model.

scholarly journals An Investigation of a Mathematical Model for the Internal Velocity Profile of Conical Diffusers Applied to DAWTs

2015 ◽  
Vol 87 (2) ◽  
pp. 1133-1148 ◽  
Author(s):  
DISTERFANO L.M. BARBOSA ◽  
JERSON R.P. VAZ ◽  
SÁVIO W.O. FIGUEIREDO ◽  
MARCELO DE OLIVEIRA E SILVA ◽  
ERB F. LINS ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Velocity Field ◽  
Arbitrary Point ◽  
Power Coefficient ◽  
Proposed Model ◽  
Axis Of Symmetry ◽  
Technology Aids ◽  
Internal Velocity ◽  
Good Agreement

The Diffuser Augmented Wind Turbines (DAWTs) have been widely studied, since the diffusers improve the power coefficient of the wind turbine, particularly of small systems. The diffuser is a device which has the function of causing an increase on the flow velocity through the wind rotor plane due to pressure drop downstream, therefore resulting in an increase of the rotor power coefficient. This technology aids the turbine to exceed the Betz limit, which states that the maximum kinetic energy extracted from the flow is 59.26%. Thus, the present study proposes a mathematical model describing the behavior of the internal velocity for three conical diffusers, taking into account the characteristics of flow around them. The proposed model is based on the Biot-Savart's Law, in which the vortex filament induces a velocity field at an arbitrary point on the axis of symmetry of the diffusers. The results are compared with experimental data obtained for the three diffusers, and present good agreement.

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