Abstract: The disclosed method of measuring the flow of a fluid with a porous particulate ceramic tracer and an optical instrument is characterized in that spherical particles having diameters in the range of 0.5 to 150 ?m are used as the tracer. Inasmuch as the tracer particles for flow measurement are spherical, the sectional area of scattered light to be detected by an optical sensor means is constant regardless of the orientation of particles. Furthermore, spherical particles have no surface irregularities that might cause concatenation so that individual particles are not agglomerated in tracking a fluid flow, thus contributing to improved measurement accuracy.

Abstract: In the method for measuring the velocity of fluid or visualizing the distribution of fluid by feeding tracer particles to the fluid, irradiating the fluid with light and observing return light from the tracer particles, tracer particles containing a flourescent substance are fed at least partially to the fluid and the fluid is irradiated with exciting light to cause the tracer particles to output flourescent emissions. A filter which does not transmit the exciting light is used to substantially selectively observe the flourecent emissions of the tracer particles. This method results in a remarkable improvement in the accuracy of flow velocity measurement or visualization of fluid distribution. Moreover, in a mixed fluid system consisting of two or more different fluids, the pattern of behavior of each fluid and the intermingled state of the fluids can be observed by using a plurality of different tracer particles.

Abstract: In the method for measuring the velocity of fluid or visualizing the distribution of fluid by feeding tracer particles to the fluid, irradiating the fluid with light and observing return light from the tracer particles, tracer particles containing a flourescent substance are fed at least partially to the fluid and the fluid is irradiated with exciting light to cause the tracer particles to output flourescent emissions. A filter which does not transmit the exciting light is used to substantially selectively observe the flourecent emissions of the tracer particles. This method results in a remarkable improvement in the accuracy of flow velocity measurement or visualization of fluid distribution. Moreover, in a mixed fluid system consisting of two or more different fluids, the pattern of behavior of each fluid and the intermingled state of the fluids can be observed by using a plurality of different tracer particles.

Abstract: The disclosed method of measuring the flow of a fluid with a porous particulate ceramic tracer and an optical instrument is characterized in that spherical particles having diameters in the range of 0.5 to 150 ?m are used as the tracer. Inasmuch as the tracer particles for flow measurement are spherical, the sectional area of scattered light to be detected by an optical sensor means is constant regardless of the orientation of particles. Furthermore, spherical particles have no surface irregularities that might cause concatenation so that individual particles are not agglomerated in tracking a fluid flow, thus contributing to improved measurement accuracy.

Abstract: In the method for measuring the velocity of fluid or visualizing the distribution of fluid by feeding tracer particles to the fluid, irradiating the fluid with light and observing return light from the tracer particles, tracer particles containing a flourescent substance are fed at least partially to the fluid and the fluid is irradiated with exciting light to cause the tracer particles to output flourescent emissions. A filter which does not transmit the exciting light is used to substantially selectively observe the flourecent emissions of the tracer particles. This method results in a remarkable improvement in the accuracy of flow velocity measurement or visualization of fluid distribution. Moreover, in a mixed fluid system consisting of two or more different fluids, the pattern of behavior of each fluid and the intermingled state of the fluids can be observed by using a plurality of different tracer particles.

Abstract: The disclosed method of measuring the flow of a fluid with a porous particulate ceramic tracer and an optical instrument is characterized in that spherical particles having diameters in the range of 0.5 to 150 &mgr;m are used as the tracer. Inasmuch as the tracer particles for flow measurement are spherical, the sectional area of scattered light to be detected by an optical sensor means is constant regardless of the orientation of particles. Furthermore, spherical particles have no surface irregularities that might cause concatenation so that individual particles are not agglomerated in tracking a fluid flow, thus contributing to improved measurement accuracy.

Abstract: The disclosed method of measuring the flow of a fluid with a porous particulate ceramic tracer and an optical instrument is characterized in that spherical particles having diameters in the range of 0.5 to 150 &mgr;m are used as the tracer. Inasmuch as the tracer particles for flow measurement are spherical, the sectional area of scattered light to be detected by an optical sensor means is constant regardless of the orientation of particles. Furthermore, spherical particles have no surface irregularities that might cause concatenation so that individual particles are not agglomerated in tracking a fluid flow, thus contributing to improved measurement accuracy.

Abstract: In the method for measuring the velocity of fluid or visualizing the distribution of fluid by feeding tracer particles to the fluid, irradiating the fluid with light and observing return light from the tracer particles, tracer particles containing a fluorescent substance are fed at least partially to the fluid and the fluid is irradiated with exciting light to cause the tracer particles to output fluorescent emissions. A filter which does not transmit the exciting light is used to substantially selectively observe the fluorescent emissions of the tracer particles. This method results in a remarkable improvement in the accuracy of flow velocity measurement or visualization of fluid distribution. Moreover, in a mixed fluid system consisting of two or more different fluids, the pattern of behavior of each fluid and the intermingled state of the fluids can be observed by using a plurality of different tracer particles.

Abstract: The disclosed method of measuring the flow of a fluid with a porous particulate ceramic tracer and an optical instrument is characterized in that spherical particles having diameters in the range of 0.5 to 150 .mu.m are used as the tracer. Inasmuch as the tracer particles for flow measurement are spherical, the sectional area of scattered light to be detected by an optical sensor means is constant regardless of the orientation of particles. Furthermore, spherical particles have no surface irregularities that might cause concatenation so that individual particles are not agglomerated in tracking a fluid flow, thus contributing to improved measurement accuracy.

Abstract: In the method for measuring the velocity of fluid or visualizing the distribution of fluid by feeding tracer particles to the fluid, irradiating the fluid with light and observing return light from the tracer particles, tracer particles containing a fluorescent substance are fed at least partially to the fluid and the fluid is irradiated with exciting light to cause the tracer particles to output fluorescent emissions. A filter which does not transmit the exciting light is used to substantially selectively observe the fluorescent emissions of the tracer particles. This method results in a remarkable improvement in the accuracy of flow velocity measurement or visualization of fluid distribution. Moreover, in a mixed fluid system consisting of two or more different fluids, the pattern of behavior of each fluid and the intermingled state of the fluids can be observed by using a plurality of different tracer particles.

Abstract: A method of producing uniform inorganic microspheres with a particle size of 0.01 to 500 .mu.m by injecting an aqueous solution containing a particle-forming material into an organic solvent. The method includes injecting the aqueous solution into the organic solvent through a macromolecular membrane having a hydrophobic surface and having pores substantially uniform in pore size and extending in the direction of thickness of the membrane, substantially straight through the membrane, so that a path length of each of the pores corresponds substantially to a thickness of the membrane, to form, in said organic solvent, a large number of emulsion particles substantially uniform in size and then producing uniform inorganic microspheres from said emulsion particles on a one emulsion particle-to-one microsphere basis. The pores in the membrane are formed by either a corpuscular or laser beam.