Laser Light Sheet Method Research Articles

Experimental and numerical evaluation of drug release from nanofiber mats to brain tissue.

Drug delivery systems based on nanofibrous mats appear to be a promising healing practice for preventing brain neurodegeneration after surgery. One of the problems encountered during planning and constructing optimal delivery system based on nanofibrous mats is the estimation of parameters crucial for predicting drug release dynamics. This study describes our experimental setup allowing for spatial and temporary evaluation of drug release from nanofibrous polymers to obtain data necessary to validate appropriate numerical models. We applied laser light sheet method to illuminate released fluorescent drug analog and CCD camera for imaging selected cross-section of the investigated volume. Transparent hydrogel was used as a brain tissue phantom. The proposed setup allows for continuous observation of drug analog (fluorescent dye) diffusion for time span of several weeks. Images captured at selected time intervals were processed to determine concentration profiles and drug release kinetics. We used presented method to evaluate drug release from several polymers to validate numerical model used for optimizing nanofiber system for neuroprotective dressing.

G0600-2-4 衝突噴流群を用いた流路内の流動および熱移動解析(熱工学部門一般講演(2):伝熱(2))

This paper shows the influence of flow behavior of multiple impingement jets on characteristics of heat transfer of narrow spaces. The jets were set a 5×5 nozzles of sharp edged orifice type with D=5 mm in diameter. The jet-to-jet space is 10 mm. The experiments were performed for the separation distance, H, between jet exit and impingement plate ranging from H/D=1 to 3, at Reynolds number 1600〜3300. The time and spatial temperature profiles over the impingement plate were measured using at infrared camera (TVS-8500, Avio) with a two-dimensional array of Indeum-Antimony (In Sb) sensors. To clarify the influence of the flow behavior on heat transfer fields, we visualized a smoke flow field by means of a laser light sheet method (LLS). Based on these experimental data, the relationships between the fluid flow and the heat transfer characteristics were clarified.

Experimental Investigation of the Cooling Flow in the Film Blowing Process

Abstract The film blowing process relies on external air cooling of the extruded polymer hose. The air is supplied by a ring nozzle surrounding the die. We investigate the flow as it emanates from a commercial nozzle by a laser light sheet method which reveals the instantaneous rather than the mean flow structure. Flow separation in the nozzle is diagnosed as well as a high degree of disturbances affecting the thermal boundary layer. To improve the flow a modified nozzle is investigated in the same way, which shows how separation is avoided and how the regular structure of a wall jet is attained. The limits of this approach are highlighted. The optical measurements are amended by pressure measurements inside and outside the nozzle. They show what the flow disturbances mean in terms of normal forces on the film.

Separation of Condensation Jet Image Using Filter Effect of Wavelets Transform

The present paper describes the application of discrete wavelet transform to the analysis of condensation jets in order to clarify the fluid and heat transfer phenomenon. The condensation jets in the nozzle vicinity are experimentally visualized via the laser light sheet method to obtain condensation particle density images of the jets. The image of the condensation particle density in the jet is decomposed to mean and fluctuation images via wavelet multiresolution. The dominant temperature boundary and the mean component outside the boundary were obtained from wavelet separation images. The boundary was compared to the experimentally obtained temperature distribution.

201 拡大管内における球まわりの流れの研究(G05-2 物体周りの流れ,G05 流体工学)

In order to investigate the relation between a flow structure and a sphere behavior in a diverging funnel, an observation of the sphere behavior and flow visualization in the diverging runnel by the laser light sheet method were carried out. The sphere behavior could be classified into two categories i.e., pattern (a): the sphere lifts toward the flow direction with a rotation, and pattern (b): the sphere lifts with a rotation also a revolution along the cannel wall. The sphere lift distance decreases as the funnel angle increases and the sphere weight gains. The time delay, which the cease of the sphere motion takes since the mainstream stops, depends on the kinetic energy of the sphere, the gravity of the sphere and the resistance force acting on the sphere that are increase as the sphere size increases, respectively.

910 一様水流中の柔軟な弾性膜に発生するフラッタリング(GS-2 バイオエンジニアリング(2))

The fish's thrust results from actions of swimming fish that the fish's body is made to generate traveling waves by bending itself and transmits them downward. We think that fluttering has the possibility of drag reduction because it generates some thrust and assists main power. So we focus on fluttering in fluid. Study of fluttering was done using various kinds of elastic sheets having high and low stiffness. Our experimental models consisted of a flexible rear made of a very thin silicone rubber sheet which was easily deformed and a rigid front made of stainless steel. It was placed in a water tunnel. A laser light sheet method was used to visualize the deformation of the flexible sheet and the flow field around the model. From the visualization experiments, we measured the wave velocity, wavelength, frequency and amplitude of traveling wave on fluttering of a flexible sheet. We calculated fluttering of a flexible sheet with the model that the wave form was assumed and the principle of the energy conservation.

小型渦発生ジェットに関する研究 : 発生渦の可視化と速度分布(G05-11 渦・噴流,G05 流体工学部門一般講演)

In order to control the vortex structure within a turbulent boundary layer, the small vortex generating jet was applied. The visualization and analysis of a generating vortex in each jet conditions by the laser light sheet method using YAG laser were performed. Moreover, comparison with the speed distribution measured using the hot wire flow velocity meter performed before was carried out. It turns out that the vortex by which the time of jet angle α=45° was stabilized most is generated from this result.

MEMSセンサとレーザーライトシート法を用いた乱流チャンネル内周期渦の解析(OS12-3 フュージョンテクノロジーによるビジュアリゼーション(産業と応用))

MEMSセンサとレーザーライトシート法を用いた乱流チャンネル内周期渦の解析(OS12-3 フュージョンテクノロジーによるビジュアリゼーション(産業と応用))

A222 フラクタル次元解析による非定常噴流の形状特性

Explanation of injected fuel and air mixture formation process in combustion chamber is necessary to reduce exhaust gas of a car. The shape of fuel jet is shown quantitatively by fractal dimension. And the unsteady jet shape characteristic is clarified. Till now, helium jet has been visualized by the Schilieren method. By this method, the three dimensional data on a jet is photography in two dimensions, and it cannot extract only the outline of a jet. So water jet with tracer is injected into a water, and the two dimensional section of a jet was visualized by the laser light sheet method. The photograph of jet is taken by high speed camera. The outline of jet was extracted by image processing. The jet shape characteristic was found by searching for a fractal dimension. And it becomes clear that the jet shape characteristic changes with differences in nozzle shape (diameter and length).

A221 平板に衝突する非定常噴流の濃度特性

To improve the combustion efficiency in a direct injection engine, it is important to improve the mixture formation on the combustion chamber wall. In the gas injection in the atmosphere flow is high-speed and analysis is difficult. Then, the jet is changed into the low-speed liquid injection in liquid by the similarity rule of a flow. The influence by the angle of a plate (modeled the piston head) analyzed the concentration characteristic of an unsteady impinging jet with the photograph visualized by the laser light sheet method of Ar+. Understood the process of development of the unsteady jet by after injection start. Development of the unsteady jet by the difference in the angle of plate was also observed. It becomes a clue in a solution to the trade-off of NOx and soot from the concentration character of unsteady impinging jet.

Experimental Study on the Flow Induced by a Suddenly Accelerated Concentric Rotating Drum (Measurements of Angular and Radial Velocity Distribution by Using LDV)

An experimental study is performed to disclose the unsteady flow inside a rotating drum induced by an impulsive start of motion. Laser Doppler velocimeter (LDV) is employed to determine the distribution of both the angular and radial velocity components in the flow field on the meridional plane in the rotating drum. The laser light sheet method is also engaged to enable visualization of flow patterns. Fluid viscosity, drum size and rotational speed are varied to determine their effects on the flow. From these results, the time history of the distribution of both the angular and radial velocity are disclosed. The time history of Ekman boundary layer thickness are also determined from radial velocity distribution.

ウェーブレット多重解像度を用いた凝縮噴流の温度分布解析

This experimental study aims at investigating temperature distribution of condensation jets in the free shear layer using wavelets multiresolution. Cold dry air is discharged from a round nozzle of 10 mm in diameter into the high humidity environment. For temperature measurement, the fine thermo couple is used. It is observed from the visualization photograph using laser light sheet method that condensed particles exist around the free shear layer. From the measurement the particle increase and spreads toward surroundings as the humidity rises. The dominant temperature boundary and the mean component outside boundary were provided from wavelet separation images. These boundaries were compared with the temperature distribution provided from the experimental result.

Transient Wave Traveling on the Surface of Elasto-Flexible Cylinder in Uniform Water Flow.

It is important to bio-fluidmechanics to understand the interaction among deformable surface, its surrounding flow field and hydrodynamical forces. In order to clarify this interaction, we have been using cylinder models having an elasto-flexible surface in uniform water flow. The laser light sheet method was used to visualize the deformation of the surface and the flow field around it. The experimental result showed that there were three different kinds of traveling wave generated on the surface, namely, a continuously-occurring wave, a periodically-occurring wave and a randomly occurring wave. In the case of the periodical and continuous waves, the frequencies of the waves were 6 to 9 times higher than that of the Karman vortex pair shedding from the rigid cylinder. Their wavelengths were about 1/8 compared with the theoretical wavelength of the Karman vortex street behind the rigid cylinder. It is indicated that generation of the wave was not caused by large pressure variation from the vortex shedding. The visualization results suggest that local pressure decrease flow separation from the surface and by the generation and moement of the small vortex were responsible for the apperarance and the propagation of the transient wave.

Drag Reduction and Its Application. Drag Reduction Caused by Traveling Wave Occurring on the Surface of Elasto-Flexible Cylinder.

It is important to fluid mechanics and bio-fluid mechanics to understand an interaction among deformable surface, its surface, its surrounding flow field and hydrodynamical forces. In order to clarify this interaction by experiments, we have been using several cylinder models having an elasto-flexible surface in uniform water flow. The hydrodynamic forces were measured by a three-component force balance. The deformation of the surface and the flow field around it were visualized using a laser light sheet method simultaneously. The experimental results showed that the time-averaged hydrodynamical drag was approximately 20% lower than that of the rigid cylinder when the continuously occurring wave appeared on the surface. In the case of the drag reduction occurrence, the power spectra of the lift fluctuation were broadened and had several peaks. In particular, the prominent frequency of power spectrum was about 45% lower than the frequency in the cases of the rigid cylinder and of no drag reduction occurring. The visualization results suggested that the strength of the Karman vortex shed from the cylinder was decreased compared with that from the rigid cylinder and this decrease was responsible for the above mentioned drag reduction.

三次元境界層剥離の可視化と熱線計測

The flow in the cross-flow separation of an axisymmetric paraboloid at 30, 40 and 50 deg angle of attack has been investigated experimentally by smoke visualization technique and hot wire anemometer. Reynolds numbers are 9.0×103 and 1.8×104 referred to the base diameter. Laser light sheet method is used in studying the structure of the vortices in cross-sectional flow. The development of streamwise vortices in each section of the body is visualized. X-type probe was used to measure three dimensional velocity fields over the axisymmetric paraboloid. Velocity fluctuations at sampling time of 4 kHz have been also evaluated. The extent of longitudinal vortices, such as main, primary-and secondary vortices, and the change of r.m.s. value in various cross-sections are presented. The variation of vortex patterns is shown for each cross-section, angle of attack and Reynolds numbers. It has been confirmed that each streamwise vortex is related to the velocity fluctuations.

Two Dimensional Numerical Simulation and Experiment on Large Deformation of Collapsible Tube.

By using a tube law, which is the relationship between cross sectional area of a collapsible tube and transmural pressure, that is, the pressure difference of the inside from the outside of its wall, coupled problem between flow in the tube and its wall deformation can be formulated easily. In this paper a numerical method for calculating two-dimensional deformation of the tube and comparison with experimental results are reported. The calculation results are compared with those of ref.(6)to show validity of our calculation method in which the tube wall thickness is taken into account for contact behavior of the tube wall. In the experiment we use silicone rubber tubes as the collapsible tube. The tube's cross sectional shape is visualized by using laser light sheet method. It is shown experimentally that the tube law calculated by dividing inner volume of the tube by its length has large error in the wall contact region. In the tube law calculated in ref.(6), the tube wall thickness is not treated in rigorous way in the wall contact region. But according to our results, effect of the wall thickness on the tube law is not negligible in the contact region.

拘束噴流内の大規模構造の解析

Flow visualization using Laser Light Sheet method was carried out to observe the large scale eddies in bounded jet. In order to reveal flow structure of a turbulent bounded jet in terms of period and time delay, the wavelet cross-correlation analysis was employed to analyze cross-correlation relationships between X-components of the fluctu-ating velocities at two different points near the wall in the near field. From the distribu-tions of the wavelet cross-correlation coefficients, similar structures of eddy motions with various scales were shown and branching of eddy structures was observed. The periodic eddy motions can be easily determined in terms of period and delay time. The large scale structure in bounded jet has been confirmed, comparing the information from flow visualization with the result of analysis.

Two-Dimensional Numerical Simulation and Experiment on Large Deformation of Collapsible Tube.

By using the tube law, which describes the relationship between the cross-sectional area of a collapsible tube and the transmural pressure, which is the difference between inside pressure and outside pressure, a coupled problem between flow in the tube and wall deformation is formulated. In this paper, a numerical method for calculating two-dimensional deformation of the tube is presented and the results are compared with experimental results. The calculation results are compared with those of Ref. (6) to show the validity of our calculation method in which tube wall thickness is taken into account in determining the contact behavior of the tube wall. In the experiment, we use a silicone rubber tube as the collapsible tube. The tube's cross-sectional shape is visualized by using the laser light sheet method. It is shown experimentally that the tube law calculated by dividing the inner volume of the tube by its length has a large error in the wall contact region. In the calculation in Ref.(6), tube wall thickness is not treated rigorously in the wall contact region. However, according to our results, the effect of wall thickness on the tube law is not negligible in the wall contact region.

Visualization of aerodynamic effects on a double-delta wing aircraft model using Pressure Sensitive Paint (PSP) technique

Visualization of aerodynamic effects on a three-dimensional double-delta wing aircraft model was conducted using an optical pressure measurement system, based on the Pressure Sensitive Paint (PSP) technique, and in addition a laser-light sheet method. The combination of PSP technology with the laser-light sheet method, provides a good understanding of the flow around the wind tunnel model. In recent years, this novel PSP-technology has attracted considerable attention in the aerospace community. The PSP technique can be used to realize absolute pressure measurements on a surface of a model and in addition to evaluate quantitative aerodynamic flow phenomena using a scientific grade camera and image processing techniques. The PSP system was tested in the Transonic Wind Tunnel of the German Aerospace Center in Gottingen (TWG) under real flow conditions. Instantaneous pressure distributions are recorded in almost real-time so that the recognition and analysis of the vortex dynamics on the model surface is possible. Even the vortex breakdown process, as well as the fine structured Kelvin-Helmholtz instabilities and secondary vortex structures, can be detected by this measurement technique.

Analysis of Flow Field in Diesel Fuel Sprays by Particle-Image Velocimetry.

The characteristics of combustion process in internal combustion engines are affected by mixing process between the injected fuel and the ambient gas. Therefore, it is necessary to understand the flow field in diesel fuel sprays. In this study, a single spray was injected into a quiescent atmosphere with room temperature at high pressure through a single hole nozzle for simplification. To discuss the flow field in diesel sprays, structure of the spray was visualized by laser light sheet method. And, it was revealed that the vortex structure inside the spray affects the classification of droplet particles by taking microscopic photographs of the droplets with high resolution film. And applying PIV method into the spray photography, both the formation of meandering structure of the spray mainstream and the ambient gas entrainment process are clarified.