Experimental and Numerical Evaluation of Small-Scale Cryosurgery Using Ultrafine Cryoprobe

2013 ◽  
Author(s):  
Junnosuke Okajima ◽  
Atsuki Komiya ◽  
Shigenao Maruyama
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Biological Tissue ◽  
Bioheat Transfer ◽  
Small Scale ◽  
Outer Diameter ◽  
Two Phase ◽  
Inner Diameter ◽  
Surgical Treatments ◽  
Tube Structure

Cryosurgery is one of the surgical treatments using a frozen phenomenon in biological tissue. In order to reduce the invasiveness of cryosurgery, the miniaturization of cryoprobe, which is a cooling device for cryosurgery, has been required. The authors have developed a ultrafine cryoprobe for realizing low-invasive cryosurgery by the local freezing. The objective of this study is to evaluate the small-scale cryosurgery using the ultrafine cryoprobe experimentally and numerically. The ultrafine cryoprobe has a double-tube structure and consists of two stainless microtube. The outer diameter of ultrafine cryoprobe was 550 μm. The inner tube, which has 70 μm in inner diameter, depressurizes the high-pressure liquidized refrigerant. Depressurized refrigerant changes its state to two-phase and passes through the gap between outer and inner tube. The alternative Freon of HFC-23 was used as a refrigerant, which has the boiling point of −82°C at 0.1 MPa. The cooling performance of this ultrafine cryoprobe was tested by the freezing experiment of the gelated water kept at 37°C. The gelated water at 37°C is a substitute of the biological tissue. As a result of the cooling in 1 minute, the surface temperature of the ultrafine cryoprobe was reached at −35°C and the radius of frozen region was 2 mm. In order to evaluate the temperature distribution in the frozen region, the numerical simulation was conducted. The two-dimensional axisymmetric bioheat transfer equation with phase change was solved. By using the result from the numerical simulation, the temperature distribution in the frozen region and expected necrosis area is discussed.

Experimental and Numerical Evaluation of Small-Scale Cryosurgery Using Ultrafine Cryoprobe

2013 ◽  
Vol 4 (4) ◽  
Author(s):  
Junnosuke Okajima ◽  
Atsuki Komiya ◽  
Shigenao Maruyama
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Transfer Coefficient ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Numerical Evaluation ◽  
Small Scale ◽  
Outer Diameter ◽  
Cooling Performance ◽  
The Heat Transfer Coefficient

The objective of this work is to experimentally and numerically evaluate small-scale cryosurgery using an ultrafine cryoprobe. The outer diameter (OD) of the cryoprobe was 550 μm. The cooling performance of the cryoprobe was tested with a freezing experiment using hydrogel at 37 °C. As a result of 1 min of cooling, the surface temperature of the cryoprobe reached −35 °C and the radius of the frozen region was 2 mm. To evaluate the temperature distribution, a numerical simulation was conducted. The temperature distribution in the frozen region and the heat transfer coefficient was discussed.

scholarly journals Flow topologies in bubble-induced turbulence: a direct numerical simulation analysis

2018 ◽  
Vol 857 ◽  
pp. 270-290 ◽  
Author(s):  
Josef Hasslberger ◽  
Markus Klein ◽  
Nilanjan Chakraborty
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Flows ◽  
Volume Fraction ◽  
Fluid Velocity ◽  
Small Scale ◽  
Flow Topology ◽  
Two Phase ◽  
Local Flow ◽  
Interface Curvature

This paper presents a detailed investigation of flow topologies in bubble-induced two-phase turbulence. Two freely moving and deforming air bubbles that have been suspended in liquid water under counterflow conditions have been considered for this analysis. The direct numerical simulation data considered here are based on the one-fluid formulation of the two-phase flow governing equations. To study the development of coherent structures, a local flow topology analysis is performed. Using the invariants of the velocity gradient tensor, all possible small-scale flow structures can be categorized into two nodal and two focal topologies for incompressible turbulent flows. The volume fraction of focal topologies in the gaseous phase is consistently higher than in the surrounding liquid phase. This observation has been argued to be linked to a strong vorticity production at the regions of simultaneous high fluid velocity and high interface curvature. Depending on the regime (steady/laminar or unsteady/turbulent), additional effects related to the density and viscosity jump at the interface influence the behaviour. The analysis also points to a specific term of the vorticity transport equation as being responsible for the induction of vortical motion at the interface. Besides the known mechanisms, this term, related to surface tension and gradients of interface curvature, represents another potential source of turbulence production that lends itself to further investigation.

Numerical Simulation of Two Phase Change Materials Melting Process

2014 ◽  
Vol 1049-1050 ◽  
pp. 94-100
Author(s):  
Bo Bo Zhang ◽  
Yu Ming Xing ◽  
Qiang Sheng
Keyword(s):  
Numerical Simulation ◽  
Energy Storage ◽  
Temperature Distribution ◽  
Phase Change ◽  
Latent Heat ◽  
Control Function ◽  
Melting Process ◽  
Thermal Control ◽  
Heat Energy ◽  
Two Phase

Phase change thermal control technology has gained increasing focus as an emerging technology for the thermal control of spacecraft. This literature focused on melting process inside a latent heat energy storage filled with phase change material (PCM) by numerical simulation. A matrix-based enthalpy porosity theory in a three-dimensional finite volume discretization is simulated. The temperature distribution during the melting process of PCM Cerrolow-136 and CH3COONa·3H2O is obtained, based on which the thermal control function and energy storage capacity is compared. The results show that Cerrolow-136 has better performance. In different states of phase change, the temperature distribution of Cerrolow-136 is fairly uniform. Thermal control face's temperature of Cerrolow-136 is closer to phase transition temperature. In the same heat flux of 3000 W/m2, The whole process of thermal control temperature getting to 80°C for Cerrolow-136 is longer. Cerrolow-136, for its excellent characteristics, has potentially broad application in the fields of latent heat energy storage and space vehicle electronics.

Estimation of temperature distribution in biological tissue by using solutions of bioheat transfer equation

2008 ◽  
Vol 37 (6) ◽  
pp. 374-386 ◽  
Author(s):  
Shigenao Maruyama ◽  
Junnosuke Okajima ◽  
Atsuki Komiya ◽  
Hiroki Takeda
Keyword(s):  
Temperature Distribution ◽  
Biological Tissue ◽  
Transfer Equation ◽  
Bioheat Transfer ◽  
Bioheat Transfer Equation

scholarly journals DESIGN AND MANUFACTURE CHASSIS AND BODY OF SIMPLE GOKART USING AUTOMATIC CLUTCH AND 7.5 HP ENGINE POWER

2020 ◽  
Vol 10 (2) ◽  
pp. 43-46
Author(s):  
N. Nazaruddin ◽  
Dedy Masnur ◽  
Erwin Ardiansyah
Keyword(s):  
Engineering Students ◽  
Small Scale ◽  
Outer Diameter ◽  
Mixture Ratio ◽  
Wheeled Vehicle ◽  
Inner Diameter ◽  
The University ◽  
Design And Manufacture ◽  
Motor Sports ◽  
Engine Power

Go-kart is a variant of a simple and small open-roof four-wheeled vehicle for motor sports. Go-kart usually races on small scale circuits. Go-kart racing is usually considered a stepping stone for motor sports that are higher and more expensive. The design of the karts is carried out by mechanical engineering students of the University of Riau based on the size of karts in general. The chassis is made of pipe with ASTM A53 pipe specifications with a tensile strength of 240 MPa with a dimension of length of 6.22 meters, an outer diameter of 33.40 mm and an inner diameter of 30.02 mm. Body building is done with fiber with a catalyst mixture ratio of 1:45. The process of painting with a ratio of primers and hardeners is 1: 4, and clear and hardener 4: 1. A kart with a chassis mass of 7.09 kg and a passenger of 70 kg has been produced, with dimensions of length 1100 mm, width of 610 mm, and distance between axes of 1050 mm. This karting uses the 1994 Astra grand engine with 7.5 HP of power, 6000 rpm rotation and 20 kg mass. The transmission system used is a double automatic type.

Simulation Research of Interior Ballistics Performance for a New-Type Light Caliber Cannon

2013 ◽  
Vol 446-447 ◽  
pp. 458-462
Author(s):  
Jia Ning Li ◽  
Xin Liao ◽  
Feng Qiang Nan
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Phase Flow ◽  
Gas Temperature ◽  
Projectile Velocity ◽  
Two Phase ◽  
Simulation Research ◽  
Interior Ballistics ◽  
New Type ◽  
Simulation Results

In order to make a precise interpret and research of interior ballistics performance for a new-type light caliber cannon, an interior ballistics mathematical and physical model was established, on the basis of two-phase flow interior ballistics theory and description of interior ballistic cycle. MATLAB software was used to conduct numerical simulation. Conclusion indicates that the simulation results manifest favorable consistency with the experiment results. Simulation results can comprehensively interpret the physical process in guns by pressure distribution, projectile velocity and gas temperature distribution.

Study on Novel MEMS Hollow Microneedle Array

2007 ◽  
Author(s):  
Shuhai Jia ◽  
Yigui Li ◽  
Xiao Sun ◽  
Jun Zhu
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Outer Diameter ◽  
Microneedle Array ◽  
X Ray ◽  
Hollow Microneedle ◽  
Development Procedure ◽  
Inner Diameter ◽  
Exposure Technique ◽  
Mechanical Characters

A novel MEMS hollow microneedle array is fabricated through the exposure technique in deep X-ray lithography and development procedure in this paper. The method to fabricate microneedle array presented in this paper needn’t any special apparatuses, and is very easy to operate. A method to compensate the beam distribution of synchrotron radiation light source is described. The PMMA (polymethylmethacrylate) sheet is chosen as the material of microneedle. The length of the hollow microneedle fabricated is 160μ m. The outer diameter of microneedle is 80μm, and the inner diameter of microneedle is 40μm. The mechanical characters of microneedle, such as the force withstanding capabilities, are studied through both the theoretical analysis and numerical simulation of finite element method. The analysis results of the mechanical character show that the strength of microneedles fabricated in this paper is enough to pierce human skin.

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