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  • The PHOENICS Input-file Library
    the default answers to the READVDU questions One file namely Q1EARS HTM provides access to the whole content of the library It lists all cases grouped under the headings core library option libraries and special purpose program libraries Each item is represent by one line such as Q1 f402 Two phase flow in a bifurcation followed by a few more such as only 1 interval in Z direction two phase flow solves for turbulent kinetic energy solves for turbulent energy dissipation fiinit prps 1 so use PIL properties for domain fluid involves buoyancy uses PARSOL for partly solid cells material indices set via SPEDAT which mention some points of possible interest to users The Q1 is a hyperlink which leads directly to the Q1 file itslf while the charecters following the Q1 are both the unique identifier of the case in question and a hyperlink to the Q1EAR file The origin of the option idea is explained here It is still useful as a rough guide to what is to be found in each library but as the number of features which can be simultaneously activated has increased its usefulness has diminished Users wishing to find out in more detail where to find items which may interest them are therefore advised to make use of the library search facility which is now to be described 2 How to find library cases It is of course possible to open the Q1EARS file with a browser and search for keywords expressive of the user s interests However this is somewhat laborious and it may not reveal all the cases which indeesd correspond to those interests A faster and more systematic approach is to do the following Activate the PHOENICS Commander click on the Input File Libraries button click on the How to

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/libcoa.htm (2016-02-15)
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    NXD NYD NZD PATCH SOURCE LOW 1 NXD 1 NYD 1 NZD 1 1 Integer variables can be combined by means of any of the following arithmetic operators and The operands can be any combination of integer and real numbers PIL variables array elements and user declared variables Examples are LSWEEP 10 I1 I2 NXPRIN I1 I2 I1 I1 I2 PATCH INLET LOW 1 I1 I1 I2 1 2 0

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/integ.htm (2016-02-15)
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    1987 R T Lahey The analysis of phase separation and phase distribution phenomena using two fluid models Nuclear Engng Design Vol 122 p17 1990 R T Lahey M Lopez de Bertodano O C Jones Phase distribution in complex geometry ducts Nuclear Engng Design Vol 141 p177 1993 G J Lee and S H Chang Physical modelling and finite element method for the analysis of lateral phase distribution phenomena Int Comm Heat Mass Transfer Vol 18 p333 1991 B Huang Modelisation numerique d ecoulements diphasiques a bulles dans des reacteurs chimiques PhD Thesis L Universite Claude Bernard Lyon 1989 K O Petersen Etude experimentale et numerique des ecoulements diphasiques dans les reacteurs chimiques PhD Thesis L Universite Claude Bernard Lyon 1992 C Prakash Prediction of some complex multi dimensional two phase flow phenomena using the PHOENICS code Proc 2nd Int PHOENICS Users Conference Heathrow London 1987 A Serizawa I Kataoka and I Michiyoshi Phase distribution in bubbly flow Data Set No 24 in Multiphase Science and Technology Vol 6 p257 Ed G F Hewitt J M Delhaye and N Zuber Hemisphere Publishing Corporation 1992 H F Svensen H A Jakobsen and R Torvik Local flow structures in internal loop and bubble column recators Chem Eng Sci Vol 47 No 13 14 pp3297 1992 INTERFACIAL PRESSURE SOURCES ONEPHS F Contents 1 Introduction 2 Activation 3 Exemplification and References 1 Introduction The basic form of the pressure terms in the momentum equations for two phase flow is as follows see Drew 1983 Sk i rk grad Pk Pki Pk grad rk 1 1 where Sk i is the volumetric source for phase k in direction i rk is the volume fraction of phase k Pk is the pressure of phase k in the bulk and Pki is the pressure of phase k at the interface When ONEPHS F the default in PHOENICS is to assume that there are no pressure differences between the phases i e Pk Pki P 1 2 so that equation 1 1 reduces to Sk i rk grad P 1 3 This assumption is adequate in applications which do not involve acoustic effects or bubble expansion or contraction The interfacial pressure source terms allow for the possibility of momentum transfer due to pressure discontinuities between the bulk phases and the interface The option exists for these effects to be included in the PHOENICS momentum equations for two phase flow via the source terms 1 1 above PHOENICS employs two alternative formulations of the interfacial pressure terms The first is the one described by Huang 1989 Lahey et al 1993 and Petersen 1992 for dispersed bubbly two phase flow The second is the one described by Stuhmiller 1977 and Prakash 1987 for the same applications Lahey Formulation The formulation of Lahey et al 1993 employs the following relationships for the pressure differences Pdi Pd 0 1 4 Pci Pc Cp rhoc Ur Ur 1 5 Pdi Pci 2 sigma k 1 6 where c denotes the continuous phase d the

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/interfa.htm (2016-02-15)
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    suddenly decreases to 0 1 as a result of the movement of the separation point towards the rear of the sphere and the boundary layer flow undergoing transition to turbulence In PHOENICS the following Cd correlations have been provided as options Standard Drag Curve see below Stokes Drag Regime Cd 24 Re Turbulent Drag Regime Cd 0 44 Subcritical Regime Cd max 0 44 24 1 0 15 Re 0 687 Re The correlation used for the Subcritical Regime is based on that of Schiller and Naumann 1933 The standard drag curve is the default option and it uses the correlations of Clift et al 1978 Cd 24 0 1 0 0 15 Re 0 687 Re 0 42 1 0 4 25E4 Re 1 16 for Re 3 38E5 3 6 Cd 29 78 5 3 LOG10 Re for 3 38E5 Re 4 0E5 3 7 Cd 0 1 LOG10 Re 0 49 for 4 0E5 Re 1 0E6 3 8 Cd 0 19 8 0E4 Re for Re 1 0E6 3 9 These correlations are taken from Table 5 1 eqn 10 and Table 5 2 eqns H I and J of Clift et al 1978 The limitations of the foregoing drag models are discussed below The model is applicable to a solid particle system but is also suitable for dispersed droplets and bubbles provided that surface tension effects are negligible as will be the case for very small gas bubbles and liquid droplets The model is restricted to rigid particles and does not allow for fluid particles to their change their shape and hence influence the drag PHOENICS provides for a distorted bubble drag model which is described below in Section 4 for more details on the distorted fluid particle regime see Clift et al 1978 Ishii and Zuber 1979 and Szekely 1979 For the case of clean fluid spheres Cd can be reduced by up to 33 due to internal circulation However even slight amounts of impurities are sufficient to eliminate this drag reduction so that the solid particle drag correlations provide a better approximation up to the particle size when distortion takes place see Clift et al 1978 The model does not account entirely for multi particle systems For example the continuous phase viscosity is used in evaluating Re rather than the apparent mixture viscosity for more details see Ishii and Zuber 1979 The model is restricted to spherical particles but can be extended to irregular shaped particles by interpreting Dp as Ds h where Ds is the diameter of the equivalent volume sphere and h is the shape factor defined by the ratio of the surface area to that of the sphere of the same volume For spherical particles h 1 but for all other shapes h 1 see Kay and Nederman 1985 Alternatively non spherical particles may be represented via different drag correlations see for example Clift et al 1978 The model does not account for compressibility effects in which case Cd becomes

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/interph.htm (2016-02-15)
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    activates calculation of momentum sources to account for virtual or added mass forces in dispersed two phase flows The command is equivalent to USOURC T PATCH VMASS CELL 1 NX 1 NY 1 NZ 1 LSTEP COVAL VMASS U1 TINY GRND4 COVAL VMASS U2 TINY GRND4 COVAL VMASS V1 TINY GRND4 COVAL VMASS V2 TINY GRND4 COVAL VMASS W1 TINY GRND4 COVAL VMASS W2 TINY GRND4 The magnitude of these forces is controlled by the empirical coefficients CVM RSG35 and CVMA RSG34 which are described under the Encyclopaedia entry VIRTUAL MASS MOMENTUM SOURCES Default values of CVM 0 5 and CVMA 0 5 are set by INTSOR but these may be changed by using INTSOR VMASS CVM CVMA INTSOR LIFT activates calculation of momentum sources to account for interfacial lift forces in dispersed two phase flows The command is equivalent to PATCH LIFT CELL 1 NX 1 NY 1 NZ 1 LSTEP COVAL LIFT U1 TINY GRND4 COVAL LIFT U2 TINY GRND4 COVAL LIFT V1 TINY GRND4 COVAL LIFT V2 TINY GRND4 COVAL LIFT W1 TINY GRND4 COVAL LIFT W2 TINY GRND4 The magnitude of the lift forces is controlled by the empirical coefficients CLIFT RSG31 and CLIFTA RSG30 which are described under the Encyclopaedia entry INTERFACIAL LIFT MOMENTUM SOURCE TERMS Default values of CLIFT 0 1 and CLIFTA 0 1 are set by INTSOR but these may be changed by using INTSOR LIFT CLIFT CLIFTA INTSOR INTPS or INTSOR INTPL activates calculation of momentum sources to account for interfacial pressure effects in dispersed fluid two phase flows The command is equivalent to PATCH INTP CELL 1 NX 1 NY 1 NZ 1 LSTEP COVAL INTP U1 TINY GRND4 COVAL INTP U2 TINY GRND4 COVAL INTP V1 TINY GRND4 COVAL INTP V2 TINY GRND4 COVAL INTP W1 TINY GRND4 COVAL

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/int.htm (2016-02-15)
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  • COSP
    The Optimisation parameters group sets configuration for the optimisation process The most important parameters to users are MinFunValue and MaxNoRun the former specifies the accepted value for the objective function if the calculated objective function is less than MinFunValue the optimisation process will stop and the results be printed out MaxNoRun specifies the maximum run number of EARTH if the run number exceeds MaxNoRun even if calculated objective function is bigger than MinFunValue the calculation will stop The In Form Group is to describe the mathematical expression with the searched constants COSP has specific limitation towards the parameters in the COSP input file NoExpVariant should be less than or equal to 128 NoMeasurVar should be less than or equal to 4 NoConst should be less than or equal to 10 4 How to run COSP 4 1 COSP file structure Once PHOENICS is installed on your local drive you will be able to see the following directory on your drive PHOENICS D ac3d D allpro D bodym D chmkin D cosp contains COSP data files examples executable and source files D earth D enviro D include D intfac D photon D polis contains the COSP documentation including this document D priv1 D shapem D satell Before starting the simulation the user needs to create an icon for RESLOOK EXE which resides in D cosp and is used to check the result during the optimisation process 4 2 How to run examples supplied 4 2 1 Preparation of files The user is advised to run examples supplied before using COSP to run his own cases To run the examples the user should only inspect the files involved but does not need to modify any of these files The user is recommended to run examples in the directory D cosp or D priv1 although COSP can be run in any working directory There are several sub directories under D cops examples To run an example case the user should copy the following files from corresponding sub directory of D cosp examples to D cosp or D priv1 Q1 file COSPDAT COSP INP A readme file in each sub directory of the examples describes the example and explains how to run it 4 2 2 Running COSP Once the data files are ready the following steps start the simulation Start the SATELLITE run by typing RUNSAT at the command prompt and then press RETURN A short description of the current case will appear on the screen Start the COSP by typing RUNCOS at the command prompt and then press RETURN The graphical monitoring window will appear on the screen 4 2 3 Inspection of results during execution As mentioned earlier the computation will be carried out in a perpetuum mobile mode until the requirement set in COSP INP is satisfied During this operation you can check the result by using a program called RESLOOK EXE Double click the RESLOOK icon which was advised to create in section 4 1 to activate it A window similar to the following Find File window shown in Figure 2 will appear and the user will need to locate the result file cosp res in the correct path Figure 2 Window for opening cosp res file Once you click the COSP RES file a Cosp controls window similar to Figure 3 will appear Figure 3 Cosp controls window In the Cosp controls window each button has its own function To reload from COSP RES file During the optimisation process results are written to COSP RES continuously Clicking on this button will reload data from COSP RES file and reveal the latest result To change the font of the result shown in the Cosp controls window To terminate the optimisation process Once this button is clicked a dialogue box will appear asking whether to Break process of Cosp iterations If you click the Yes button the optimisation process will terminate It should be noted that the optimisation process will not terminate immediately after you have confirmed to break process of Cosp iterations The simulation will only stop when the current cycle of the multi runs has finished To quit Cosp controls window It should be noted that clicking this button will only close Cosp controls window it will not terminate the optimisation process 4 2 4 Checking results The user should check the following output files COSP LST This file contains a summarisation of the investigated problem and final result If the optimisation process failed it will also describe the cause COSP RES This file contains a list of the values of the searched constants and their corresponding objective function The user can also examine its content via the RESLOOK window during the execution as described above COSP EAR This file contains the values of the variables which COSP uses to compare with experimental data RESULT file contains results from the simulation in the form of tables of numbers and line printer plots The results calculated with the last set of the constants during the optimisation process are included PHI file The user can use PHOTON to load this file in order to display the results graphically An alternative name for PHI from each run can be specified in Q1 by CSG1 command How to run user s own case 4 3 1 Modifying the data input files and Q1 When the user is ready to run his own case he should first create input files or modify the input files of the examples according to his own requirement 1 Q1 file As mentioned in section 3 1 there can be several sets of statements in Q1 each corresponding to a different set of experimental data 2 Data files inside DATA directory D cosp data this is required only if the user uses the DATA file structure The user should provide the data files as necessary 3 COSPDAT The setting of 10000 in COSPDAT does not need to be changed 4 COSP INP The user will need to modify

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/cosp.htm (2016-02-15)
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    IREGT is the current region number in the time direction Note that the GRDPWR command will only apply to the current region See GRDPWR for further details IREGX PIL integer default 1 group 3 IREGX is the current region number in the X direction Note that the GRDPWR command will only apply to the current region See GRDPWR for further details IREGY PIL integer default 1 group 4 IREGY is

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/ireg.htm (2016-02-15)
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    cell wise continuity The force on the w velocities is taken as Dp Dz In confined flows EARTH determines p by reference to slab wise mass continuity at each z in unconfined flows p has to be defined in some other way see IPARAB and PBAR 2 2 Integration procedure Because of the absence of the AH term a single sweep through the integration domain suffices However in order that the non linearity and inter connectedness of the equations can be adequately represented sufficient iteration must be conducted at each slab in order that imbalances in the equations have been adequately reduced for single sweep parabolic calculations allow no second chance 2 3 Storage implications To make one forward step in the integration sweep it is necessary to hold in computer memory the variables relating to only two slabs the local one and its immediately upstream neighbour This means that an unlimited number of slabs can be employed without any increase of computer storage This means that a very fine grid solution can be obtained because all available storage can be used for the cross stream directions 3 Implementation in PHOENICS 3 1 Storage In PHOENICS the predominant direction of a parabolic flow is always the z direction Storage is therefore provided only for the current and low slabs Attempts in GROUND coding to access high values will therefore fail 3 2 Settings To instruct PHOENICS to simulate a flow in the parabolic manner it is necessary to set PARAB T in the Q1 file LITHYD should be set to a sufficiently high value to ensure convergence LSWEEP which is used for this purpose in elliptic problems has no significance The integer IPARAB also needs to be set in order to indicate how the downstream pressure is to be computed This differs as between confined and unconfined flows and it also allows certain hyperbolic flows to be simulated economically See PHENC entry IPARAB 3 3 Grid matters It is often desirable that the lateral dimensions of the domain i e XULAST and YVLAST and or the z direction increment DZ vary with downstream distance Z so as to accord with changes to the thickness of the flow region to be analysed The PIL parameters AZXU AZYV and AZDZ enable this to be effected However it is usually preferable because more visible and more flexible to employ In Form s grid specification faciities as explained here 3 4 Downstream boundary conditions Since by definition downstream events can have no upstream influence in a parabolic situation no downstream boundary conditions are needed Moreover attempts to provide them may have undesirable effects because PHOENICS will attempt to apply them at the last slab that it knows about which is the current one Consequently simply to set PARAB T at the end of a Q1 file that had been earlier set up for an elliptic mode solution would give an undesired result For example the IZ NZ boundary condition corresponding to a fixed pressure

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/parab.htm (2016-02-15)
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