In statistical mechanics and thermodynamics the compressibility equation refers to an equation which relates the isothermal compressibility and indirectly the pressure to the structure of the liquid. It reads center math kT left frac partial rho partial p right 1 rho int d r g r 1 math 1 center where math rho math is the number density, g r is the radial distribution function and math kT left frac partial rho partial p right math is the isothermal compressibility . Using the Fourier representation of the Ornstein Zernike equation the compressibility equation 1 can be rewritten in the form center math frac 1 kT left frac partial p partial rho right frac 1 1 rho int h r d rm r frac 1 1 rho hat H 0 1 rho hat C 0 1 rho int c r d rm r math 2 center where h r and c r are the indirect and direct correlation functions respectively. The compressibility equation is one of the many integral equations in statistical mechanics . References D.A. McQuarrie, Statistical Mechanics Harper Collins Publishers 1976 Category Statistical mechanics Category Thermodynamics it Equazione di comprimibilit ru ... more details
Thermodynamics cTopic List of thermodynamic properties System properties The compressibility factor Z ... naturgass parlaktuna Chap3.pdf Properties of Natural Gases . Includes a chart of compressibility ... the temperature or the larger the pressure. Compressibility factor values are usually obtained ... is required before compressibility can be calculated. br Alternatively, the compressibility factor for specific gases can be read from generalized compressibility charts ref name Chart that plot ... The compressibility factor is defined as math Z frac V mathrm m V mathrm m text ideal gas frac p V mathrm ... gas the compressibility factor is math Z 1 math per definition. In many real world applications requirements ... compressibility factor graphs for pure gases Image Diagramma generalizzato fattore di compressibilit .jpg thumb 400px Generalized compressibility factor diagram. The unique relationship between the compressibility factor and the reduced temperature , math T r math , and the reduced pressure , math ... correlations of molecular properties. As for the compressibility of gases, the principle ... , and reduced pressure, math P r math , should have the same compressibility factor. The reduced temperature ... PVT data for real gases varies from one pure gas to another. However, when the compressibility factors ... , are used to normalize the compressibility factor data. Figure 2 is an example of a generalized compressibility factor graph derived from hundreds of experimental PVT data points of 10 pure gases ... and steam. There are more detailed generalized compressibility factor graphs based on as many as 25 ... values of 0.3 0.6. The generalized compressibility factor graphs may be considerably in error for strongly ... to improve the accuracy of predicting their compressibility factors when using the generalized graphs ... compressibility factors Experimental values It is extremely difficult to generalize at what pressures ... and therefore with significant intermolecular forces, the experimental value for the compressibility ... more details
0Z zero Z or 0 Z may refer to 0Z, or zero protons see Atomic number 0z, notation for no degree of redshift 0Z, a data set in statistics where the Standard score is zero 0Z, a Compressibility factor or zero See also Z0 disambiguation Letter NumberCombDisambig ... more details
Elektrolytdatenbank Regensburg abridged ELDAR is a compilation of thermodynamic data, bibliography and properties of electrolytes and their solutions. History The gathering of data has begun since 1981. Content Densities, dielectric constants Thermal expansion and compressibility data Electrical conductivity data Solubility data Activity and excess molar quantity data External links http www.dechema.de Publikationen Datenbanken Detherm.html official site Database stub Category Chemical databases de Elektrolytdatenbank Regensburg ... more details
Terzaghi s Principle states that when a rock is subjected to a stress, it is opposed by the fluid pressure of pores in the rock. ref Laws and models science, engineering, and technology. C. W. Hall, pp 444. 2000. ref More specifically, Karl von Terzaghi s Principle , also known as Terzaghi s theory of one dimensional consolidation , states that all quantifiable changes in Stress physics stress to a soil compression, deformation, shear resistance are a direct result of a change in effective stress. The effective stress math sigma math is related to total stress math sigma math and the pore pressure math u math by the relationship math sigma sigma u math reading that total stress is equal to the sum of effective stress and pore water pressure. Assumptions of Terzaghi s Principle The soil is homogenous uniform in composition throughout . The soil is fully saturated zero air voids due to water content being so high . The solid particles and water are incompressible. Compression and flow are one dimensional vertical axis being the one of interest . Strain physics Strain s in the soil are relatively small. Darcy s Law is valid for all hydraulic gradients. The coefficient of permeability earth sciences permeability and the coefficient of Compressibility Earth science volume compressibility remain constant throughout the process. There is a unique relationship, independent of time, between the void ratio and effective stress. Validity Though the first 5 assumptions are either likely to hold, or deviation will have no discernible effect, experimental results contradict the final 3. Darcy s Law does not seem to hold at low hydraulic gradients, and both the coefficients of permeability and volume compressibility decrease during consolidation. This is due to the non linearity of the relationship between void ratio and effective stress, although for small stress increments assumption 7 is reasonable. Finally, the relationship between void ratio and effective stress is not indepe ... more details
equation Equation of state s Compressibility factor s Johannes Diderik van der Waals Noro Frenkel ... naturgass parlaktuna Chap3.pdf Properties of Natural Gases . Includes a chart of compressibility ... more details
Thermodynamics cTopic Material properties The thermodynamic properties of materials are intensive thermodynamic parameters which are specific to a given material. Each is directly related to a second order differential of a thermodynamic potential . Examples for a simple 1 component system are Compressibility or its inverse, the bulk modulus Isothermal compressibility math beta T frac 1 V left frac partial V partial P right T quad frac 1 V , frac partial 2 G partial P 2 math Adiabatic compressibility math beta S frac 1 V left frac partial V partial P right S quad frac 1 V , frac partial 2 H partial P 2 math Specific heat Note the extensive property extensive analog is the heat capacity Specific heat at constant pressure math c P frac T N left frac partial S partial T right P quad frac T N , frac partial 2 G partial T 2 math Specific heat at constant volume math c V frac T N left frac partial S partial T right V quad frac T N , frac partial 2 A partial T 2 math Coefficient of thermal expansion math alpha frac 1 V left frac partial V partial T right P quad frac 1 V , frac partial 2 G partial P partial T math where P is pressure , V is volume thermodynamics volume , T is temperature , S is entropy , and N is the particle number number of particles . For a single component system, only three second derivatives are needed in order to derive all others, and so only three material properties are needed to derive all others. For a single component system, the standard three parameters are the isothermal compressibility math beta T math , the specific heat at constant pressure math c P math , and the coefficient of thermal expansion math alpha math . For example, the following equations are true math c P c V frac TV alpha 2 N beta T math math beta T beta S frac TV alpha 2 Nc P math The three standard properties are in fact the three possible second derivatives of the Gibbs free energy with respect to temperature and pressure. Sources The Dortmun ... more details
This page provides supplementary chemical data on difluoromethane . class wikitable Property Value Critical pressure p sub c sub 5.83 MPa Critical temperature T sub c sub 78.45 C 351 K Compressibility factor Z 0.9863 Specific heat capacity Heat capacity at constant pressure C sub p sub at 21 C 70 F 0.043 kJ mol sup 1 sup K sup 1 sup Specific heat capacity Heat capacity at constant volume C sub V sub at 21 C 70 F 0.034 kJ mol sup 1 sup K sup 1 sup Heat capacity ratio 1.253 Category Chemical data pages ... more details
Or date March 2011 The acentric factor math omega math is a conceptual number introduced by Pitzer in 1955, proven to be very useful in the description of matter. It has become a standard for the phase characterization of single & pure components. The other state description parameters are molecular weight , critical temperature , critical pressure , and critical volume . The a centric factor is said to be a measure of the non sphericity centricity of molecules. It is defined as math omega log 10 p rm sat r 1, rm at T r 0.7 math . where math T r frac T T c math is the reduced temperature , math p rm sat r frac p rm sat p c math is the reduced pressure saturation of vapor pressure vapors . For many monoatomic, fluids math p r rm sat rm at T r 0.7 math , is close to 0.1, therefore math omega to 0 math . In many cases, math T r 0.7 math lies above the normal boiling point boiling temperature of gases at atmosphere pressure. Values of math omega math can be determined for any fluid from math T r, p r math , and a vapor measurement from math T r 0.7K math , and for many liquid state matter is tabulated into many thermodynamical tables. The definition of math omega math gives zero value for the noble gas es argon , krypton , and xenon . Experimental data yields compressibility factors for all fluids that are correlated by the same curves when math Z math compressibility factor is represented as a function of math T r math and math p r math . This is the basis premises of three parameter theorem of corresponding states All fluids at any math omega math value, in math T r, p r const. math conditions, have about the same math Z math value, and same degree of convergence. citation needed date March 2011 See also Equation of state Reduced pressure Reduced temperature References references Category Gas laws ca Factor ac ntric de Azentrischer Faktor es Factor ac ntrico fa it Fattore acentrico ... more details
Wing twist is an aerodynamic feature added to aircraft wing s to adjust lift distribution along the wing. Often, the purpose of lift redistribution is to ensure that the wing tip is the last part of the wing surface to Stall flight stall , for example when executing a flight dynamics roll or steep climb it involves twisting the wingtip a small amount downwards in relation to the rest of the wing. This ensures that the effective angle of attack is always lower at the wingtip than at the root, meaning the root will stall before the tip. This is desirable because the aircraft s flight control surfaces are often located at the wingtip, and the variable stall characteristics of a twisted wing alert the pilot to the advancing stall while still allowing the control surfaces to remain effective, meaning the pilot can usually prevent the aircraft from stalling fully before control is completely lost. Twist that decreases the local chord s incidence from root to tip is sometimes referred to as Washout aviation washout . Twist that increases the local incidence from root to tip is less common and is called Washout aviation wash in . The X 29 had strong wash in to compensate for the additional root first stalling promoted by the forward sweep. Wing twist can also, rarely, refer to the deflection of the wing when it is made of insufficiently stiff materials actuation of the Flap aircraft flaps can, instead of deflecting air as intended, cause the wing itself to be deflected and is related to compressibility compressibility effects this problem has mostly been eradicated however, with modern high strength alloy s and carbon fiber composites . Wing twist is also observed in Insect flight insects . See also Adaptive Compliant Wing Angle of incidence Sail twist Washout aviation External links http www.aerospaceweb.org question dynamics q0055.shtml Aerospaceweb Wing Twist and Dihedral http www.aerospaceweb.org question planes q0099.shtml F 18 Hornet & Super Hornet Wing Twist Category ... more details
This is a data page for dichlorodifluoromethane . Physical properties class wikitable Property Value Density at 29.8 C gas 6.25 kg.m sup 3 sup Density at 15 C gas 5.11 kg.m sup 3 sup Triple point temperature T sub t sub 157 C 116 K Triple point pressure p sub t sub 10 Pa 0.00010 bar Critical temperature T sub c sub 112 C 385 K Critical pressure p sub c sub 4.170 MPa 41.15 bar Critical density sub c sub 4.789 mol.l sup 1 sup Latent heat of vaporization l sub v sub 166.95 kJ.kg sup 1 sup Specific heat capacity at constant pressure C sub p sub at 30 C 74 J.mol sup 1 sup .K sup 1 sup Specific heat capacity at constant volume C sub v sub at 30 C 65 J.mol sup 1 sup .K sup 1 sup Heat capacity ratio at 30 C 1.138889 Vapor pressure at 20 C 151 kPa Vapor pressure at 0 C 300 kPa Vapor pressure at 16 C 500 kPa Vapor pressure at 20 C 567 kPa Vapor pressure at 40 C 960 kPa Compressibility Compressibility Factor Z at 21 C 0.995 Viscosity at 0 C 11.68 Pa.s 0.01168 cP Thermal conductivity k at 0 C 9.46 mW.m sup 1 sup .K sup 1 sup Ozone depletion potential ODP 1.0 Trichlorofluoromethane CCl sub 3 sub F 1 Global warming potential GWP 8100 Carbon dioxide CO sub 2 sub 1 Category Chemical data pages ... more details
selfref In Wikipedia, IfD may refer to Wikipedia Images and media for deletion Images and media for deletion IFD may stand for I Fight Dragons , a Chicago based Chiptune Indie rock band. I Frame Delay Ideal free distribution Ilford railway station , England National Rail station code IFD Image File Directory, a recurring data structure within the Exchangeable image file format Exif Indentation force deflection , a measure of a foam s compressibility Independent Film Distributors , a film distribution company in Britain Indianapolis Fire Department Industrial, Flexible, and Demountable Building see portable building Information Flow Diagram Intelligent Frame Dropping Integrated Flight Deck Intensity frequency and duration Internal Fault Detector International Federation for the Roofing Trade International folk dance International Foundation for Disabled Sailing International Framework for Dictionaries IFD Library is one of the core components of the buildingSMART technology for Building Information Modeling systems Ischemic fiber degeneration Israeli folk dancing Interactive Flash Drive disambig de Ifd ... more details
In thermodynamics, the Boyle temperature is defined as the temperature for which the second virial coefficient , math B 2 T math vanishes, i.e. math B 2 T 0 math . It is at this temperature that the attractive forces and the repulsive forces acting on the gas particles balance out. Since higher order virial coefficients are generally much smaller than the second coefficient, the gas tends to behave as an ideal gas over a wider range of pressures when the temperature reaches the Boyle temperature. In any case, when the pressures are low, the second virial coefficient will be the only relevant one because the remaining concern terms of higher order on the pressure. We then have math dZ dp 0 math at math p 0 math , where Z is the compressibility factor . Defination in simple language Boyle Temperature It is the temperature at which a non ideal gas behaves like an ideal gas. At Boyle temperature ,Z 1 and B 0 gives T b a Rb Category Thermodynamics de Boyle Temperatur es Temperatura de Boyle ... more details
is based on inviscid flow theory. This compressibility correction factor also affects lift slope ... publication was in 1928 by Hermann Glauert . ref H. Glauert, The Effect of Compressibility on the Lift ... more details
NACA Report No. 836 Bending Torsion Flutter Calculations Modified by Subsonic Compressibility Corrections was issued by the United States National Advisory Committee for Aeronautics in 1946. It analyzed the problem of Aeroelasticity Flutter flutter in aircraft structures. Summary Several calculations of bending torsion wing flutter are made at two Mach number s, M 0 incompressible flow , and M 0.7 compressible flow , with the two results compared. The airfoil forces used in the M 0.7 calculation are based on refinements made by Frazer to the calculations of Possio, which were derived on the assumption of small disturbances to the main flow. For ordinary wings of normal density and of low bending frequency in comparison with torsion frequency, the compressibility correction to the flutter speed appears to be on the order of a few percent, whereas the correction to flutter speed for high density wing sections, such as a propeller, and to the wing divergence speed in general may be based on a rule using the 1 M sup 0.25 sup factor, and for M 0.7, represents a decrease on the order of 17 . The influence of the compressible properties of air on wing flutter is directly tied to the problem of determining the air forces and moments on oscillating airfoils moving at high forward speeds. This problem has been attacked by Camillo Possio L Azione aerodinamica sul profilo oscmillante in un fluido compressible a velocit iposonora. L Aerotecnica, vol. XVIII,fasc. 4, April 1838, pp. 441 468. Available as British Air Ministry Translation No. 830 , along lines indicated by Prandtl, by a procedure utilizing the pressure or acceleration potential and the method of lineariztion of the equation satisfied by the acceleration potential for small disturbances to the main flow. A review and summary ... 23, 1941 . Fraser and Skan Frazer, R. A., and Skan, Sylvia W. Influence of Compressibility on the Flexural ... conclusion to be derived from study of the numerical flutter calculations is that the effect of compressibility ... more details
Image Transonic flow patterns.svg right thumb 300px Transonic flow patterns on an aircraft wing showing the effects at critical mach. In aerodynamics , the critical Mach number Mcr of an aircraft is the lowest Mach number at which the airflow over some point of the aircraft reaches the speed of sound . ref Clancy, L.J. Aerodynamics , Section 11.6 ref For all aircraft in flight, the airflow around the aircraft is not exactly the same as the airspeed of the aircraft due to the airflow speeding up and slowing down to travel around the aircraft structure. At the Critical Mach number, local airflow in some areas near the airframe reaches the speed of sound, even though the aircraft itself has an airspeed lower than Mach 1.0. This creates a weak shock wave . At speeds faster than the Critical Mach number the drag coefficient increases suddenly, causing drag divergence Mach number dramatically increased drag ref name Clancy Ch11 Clancy, L.J., Aerodynamics , Chapter 11 ref in an aircraft not designed for transonic or supersonic speeds, changes to the airflow over the flight control surfaces lead to deterioration in control of the aircraft. ref name Clancy Ch11 In aircraft not designed to fly at or above the Critical Mach number, shock waves in the flow over the wing and tailplane are sufficient to stall the wing, make control surfaces ineffective or lead to loss of control such as Mach tuck . The phenomena associated with problems at the Critical Mach number became known as compressibility . Compressibility led to a number of accidents involving high speed military and experimental aircraft in the 1930s and 1940s. Although unknown at the time, compressibility was the cause of the phenomenon known as the sound barrier . Subsonic aircraft such as the Supermarine Spitfire , BF 109 , P 51 Mustang , Gloster Meteor , Me 262 , P 80 have relatively thick, unswept wings and are incapable of reaching Mach 1.0. In 1947, Chuck Yeager flew the Bell X 1 to Mach 1.0 and beyond, and the so ... more details
. One of the factors that must be taken into account when designing a high speed wing is compressibility ... . The significant negative effects of compressibility made it a prime issue with aeronautical engineers. Sweep theory helps mitigate the effects of compressibility in transonic and supersonic aircraft ... more details
The acoustic contrast factor is a number used to describe the relationship between the density densities and the Sound speed sound velocities or, equivalently because of the form of the expression, the densities and compressibility compressibilities of two media. It is most often used in the context of biomedical Medical ultrasonography ultrasonic imaging techniques using acoustics acoustic contrast agents and in the field of ultrasonic manipulation of particles much smaller than the wavelength using ultrasonic standing waves. In the latter context, the acoustic contrast factor is the number which, depending on its sign, tells whether a given type of particle in a given medium will be attracted to the pressure Node physics nodes or anti node s. Example particle in a medium Given the compressibilities math beta math and math beta math sub p sub and densities math rho math and math rho math sub p sub of the medium and particle, respectively, the acoustic contrast factor math phi math can be expressed as math phi frac 5 rho p 2 rho 2 rho p rho frac beta p beta math For a positive value of math phi math , the particles will be attracted to the pressure nodes, and vice versa. See also Empty section date July 2010 References reflist External links DEFAULTSORT Acoustic Contrast Factor Category Acoustics phys stub ... more details
The Volta Conference was the name given to each of the international conference s held in Italy by the Accademia dei Lincei Royal Academy of Science in Rome , and funded by the Alessandro Volta Foundation . In the interwar period , they covered a number of topics in science and humanities, alternating between the two. The first conference, held at Lake Como in 1927, led to the public introduction of the uncertainty principle by Niels Bohr and Werner Heisenberg . The second conference did not take place until 1932 its topic was Europe , and it was notable for the participation of a number of mainly fascist theorizers, along with non fascists such as the British historian Christopher Dawson . In 1933 the third conference was on the subject of immunology , and The Dramatic Theater in 1934. During this period, the influence of Italian aeronautics was gaining momentum, led by General Gaetano Arturo Crocco , an aeronautical engineer who had become interested in ramjet engines in 1931, and influenced the selection of High Velocities in Aviation for the 1935 meeting. This meeting is notable historically as it introduced a number of topics in compressibility and also included the first presentation on swept wing s by Adolf Busemann . References http history.nasa.gov SP 4219 Chapter3.html Research in Supersonic Flight and the Breaking of the Sound Barrier, Chapter 3 , John D. Anderson, Jr. sci stub Category Academic conferences Category Italian culture ... more details
In fluid mechanics , the Tait equation is an equation of state , used to relate liquid density to pressure . The equation was originally published by Peter Guthrie Tait in 1888. ref name Li cite journal last Li first Yuan Hui date 15 May 1967 title Equation of State of Water and Sea Water journal Journal of Geophysical Research location Palisades, New York volume 72 issue 10 url http www.soest.hawaii.edu oceanography faculty yhli 1967a.pdf bibcode 1967JGR....72.2665L pages 2665 doi 10.1029 JZ072i010p02665 ref It is sometimes written as math beta 0 P frac 1 V 0 P left frac partial P partial V right T frac 0.4343C V 0 P B P math or in the integrated form math V 0 P V 0 1 C log frac B P B 1 math where math beta 0 P math is the compressibility of water in units of bar unit bar sup 1 sup math V 0 math is the specific volume of water in units of litre ml gram g math B math and math C math are functions of temperature that are independent of pressure ref name Li References reflist Fluiddynamics stub Category Fluid mechanics ... more details
Image 4 11nitride.svg thumb 325px right A diagram of C sub 3 sub N sub 4 sub Beta carbon nitride C sub 3 sub N sub 4 sub is a material predicted to be harder than diamond. ref cite journal journal Nature date 5. Jun 2000 url http www.nature.com news 2000 000511 full news000511 1.html title News Crunchy filling author Ball, P. doi 10.1038 news000511 1 ref The material was first proposed in 1985 by Marvin L. Cohen Marvin Cohen and Amy Liu. Examining the nature of crystalline covalent bond bonds they theorised that carbon and nitrogen atoms could form a particularly short and strong bond in a stable crystal lattice in a ratio of 1 1.3. That this material would be harder than diamond on the Mohs scale of mineral hardness Mohs scale was first proposed in 1989. ref cite journal author Liu, A. Y. Cohen, M. L. title Prediction of New Low Compressibility Solids url http www.sciencemag.org cgi content abstract 245 4920 841 journal Science volume 245 issue 4920 doi 10.1126 science.245.4920.841 pages 841 842 year 1989 pmid 17773359 ref The material has been considered difficult to produce and could not be synthesized for many years. Recently, the production of beta carbon nitride was achieved. For example, nanosized beta carbon nitride crystals and nanorods of this material were prepared by means of an approach involving mechanochemical processing. ref cite journal author Niu, C. Lu, Y. Z. Lieber, C. M. title Experimental Realization of the Covalent Solid Carbon Nitride url http www.sciencemag.org cgi content abstract 261 5119 334 journal Science volume 261 issue 5119 page 334 337 year 1993 doi 10.1126 science.261.5119.334 ref ref cite journal author Mart n Gil, J. Mart n Gil, F. J. Sarikaya, M. Qian, M. Jos Yacam n, M. Rubio, A. title Evidence of a Low Compressibility Carbon Nitride with Defect Zincblende Structure url http link.aip.org link ?JAPIAU 81 2555 1 journal Journal of Applied Physics volume 81 issue 6 pages 2555 2559 year 1997 doi 10.1063 1.364301 ref ref cite j ... more details
Use mdy dates date September 2011 Infobox scientist name Alexandre Joel Chorin image Alexandre Chorin.jpg image size caption birth date birth place Poland nationality flagicon US American field Mathematics work institutions University of California, Berkeley UCB , Courant Institute of Mathematical Sciences Courant Institute alma mater Courant Institute of Mathematical Sciences Courant Institute doctoral advisor Peter Lax doctoral students James Sethian br Charles S. Peskin br Phillip Colella br Gary Sod known for Random vortex method br Artifial compressibility method br Projection method prizes Norbert Wiener Prize 2000 Alexandre J. Chorin born 1938 is a professor of mathematics at the University of California, Berkeley who works in applied mathematics . ref http math.berkeley.edu index.php?module mathfacultyman&MATHFACULTY MAN op sView&MATHFACULTY id 25 Alexandre Chorin at University of California, Berkeley UC Berkeley ref He is known for his contributions to the field of Computational fluid dynamics . Chorin was one of the first to develop an algorithm for the numerical solution of Incompressible Navier Stokes equation . He developed Artificial compressibility method and the immensely popular Projection method fluid dynamics Projection method . He is also responsible for the introduction of the vortex method in computational fluid dynamics. ref http www.ams.org notices 200004 comm wiener.pdf 2000 AMS SIAM Wiener Prize ref Chorin received the Norbert Wiener Prize in Applied Mathematics in 2000. ref http www.siam.org prizes sponsored wiener.php The Norbert Wiener Prize ref This prize is awarded for an outstanding contribution to applied mathematics in the highest and broadest sense . Chorin was a student of Peter D. Lax and teacher of James A. Sethian . Incidentally, both Lax and Sethian also won the Norbert Wiener Prize. Professor Chorin also holds the University of California Professor award, which has been awarded to only a handful of people. The award gives him ... more details
The Carr index also Carr s index ref Bowker, Michael I. & P. Heinrich Stahl. 2008. Preparation of Water Soluble Compounds through Salt Formation. In Camille Georges Wermuth, ed. The Practice of Medical Chemistry , pp. 747 766. Burlington, MA Elsevier, p. 756. ref or Carr s Compressibility Index ref name Podczeck Podczeck, Fridun & Brian E. Jones, eds. 2007. Pharmaceutical Capsules . London Pharmaceutical Press, p. 111. ref is an indication of the compressibility of a Powder substance powder . It is named after the pharmacologist Charles Jelleff Carr 1910 2005 . ref name Podczeck ref http www.lsro.org newsroom jeff carr.html In Memoriam Charles Jelleff Carr, Ph.D., 1910 2005 ref The Carr index is calculated by the formula math C 100 frac V T V B V T math , where math V B math is the freely settled volume of a given mass of powder, and math V T math is the tapped volume of the same mass of powder. It can also be expressed as math C 100 times 1 frac rho B rho T math , where math rho B math is the freely settled bulk density of the powder, and math rho T math is the tapped bulk density of the powder. The Carr index is frequently used in pharmaceutics as an indication of the flowability of a powder. A Carr index greater than 25 is considered to be an indication of poor flowability, and below 15, of good flowability. ref cite book author Kanig, Joseph L. Lachman, Leon Lieberman, Herbert A. title The Theory and Practice of Industrial Pharmacy publisher Lea & Febiger location Philadelphia year 1986 edition 3 isbn 0 8121 0977 5 ref The Carr index is related to the Hausner ratio , another indication of flowability, by the formula math C 100 times 1 1 H math . Both the Hausner ratio and the Carr index are sometimes criticized, despite their relationships to flowability being established empirical ly, as not having a strong theoretical basis. Use of these measures persists, however, because the equipment required to perform the analysis is relatively cheap and the technique is ... more details
Encyclopedia
top
