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  • usp.htm
    fluids are present in the same domain and the stresses in the solids are not to be calculated the cells in the solid part are used only for temperature because there are no pressures or velocities or displacements to be computed there Unstructured PHOENICS and structured PHOENICS exist simultaneously in one executable and they have much in common The points of similarity are Problem set up data are supplied via a q1 file to the Satellite and via an eardat file to EARTH The outcomes of the calculation appear in the RESULT and PHI files The graphical output to the monitor is similar in appearance The points of difference are USP require additional instructions from the user regarding the grid which is to be used Formats of the data written to the RESULT and PHI files differ somewhat and For USP the package recommended for graphical display of the results is Tecplot rather than PHOTON or VR Viewer Ready to run USP cases USP is an acronym signifying UnStructured Phoenics It denotes the feature of PHOENICS which allows to use an unstructured grid for its calculations This approach facilitates simulation of flows in thin channels calculation in domains containing a

    Original URL path: http://www.cham.co.uk/phoenics/d_pc/htms/english/newitems/usp/usp.htm (2016-02-15)
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  • ENC_TU84.HTM
    roughness is often specified in terms of a relative roughness e g equivalent protrusion height to diameter ratio in pipe flows Further information giving recommendations and formulae for the effective sand grain roughness height can be found in the literature see for example Boundary Layer Theory H Schlichting McGraw Hill 1968 4 2 Fully rough logarithmic law PHOENICS GRND5 wall functions are suitable for a fully rough near wall layer in local equilibrium defined in terms of the effective roughness height as for example in the atmospheric boundary layer These wall functions are the same as those described above for GRND2 equilibrium turbulent wall functions except for the form of the logarithmic wall law which is now given by Ur UTAU ln Y Y0 k Equation 21 where Y0 is the effective roughness height This height is related to the size of the roughness elements on the surface e g a typical value for grass is 0 01m whereas for forest it is about 1m Equation 21 implies that the absolute value of the wall shear stress can be computed from TAUW s RHO Ur 2 Equation 22 where s 0 41 ln Y0 Y 2 Equation 23 If x is a coordinate direction aligned with the surface the stress in that direction is TAUWx s RHO Ur Ux Equation 24 where Ux is the x direction velocity at the near wall grid node at distance Y from the wall For heat and mass transfer the Stanton number is computed from a modified Reynolds analogy i e St s Prt 4 3 Specification of the Roughness Height In PHOENICS there are two methods by which the user can set the roughness height for walls The roughness height can be set through the PIL variable WALLA stored in the common block

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/turmod/enc_tu84.htm (2016-02-15)
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  • WORKSHOP - Use of Linked Angled Inlets
    air It allows us to set heat sources Click Energy Source and select Fixed heat Flux Enter 5000 in the Value box to set a heat source of 5000W for the entire object Clock OK to close the Object Specification Dialogue Box HEATER will now appear in the Object Management list of objects Create the OUT L object Click on Object New and New Object Change name to OUT L Click on Size and set SIZE of object as Xsize 0 Ysize To end Zsize To end Click on Place and set Position of object as Xpos 0 0 Ypos 0 0 Zpos 0 0 Click on General Define Type OUTLET Click on then Attributes Set the external turbulence to User set The default user set extarnal values give a turbulent viscosity which is roughly laminar In many cases this is more stable than the In cell default setting which allows the external values to float Click on OK to close the Object Specification Dialogue Box Create the OUT R object Click on Object New and New Object Change name to OUT R Click on Size and set SIZE of object as Xsize 0 Ysize To end Zsize To end Click on Place and set Position of object as Xpos At end Ypos 0 0 Zpos 0 1 Click on General Define Type OUTLET Click on Attributes Set the external turbulence to User set The default user set extarnal values give a turbulent viscosity which is roughly laminar In many cases this is more stable than the In cell default setting which allows the external values to float Click on OK to close the Object Specification Dialogue Box Create the INTAKE object Click on Object New and New Object Change name to INTAKE Click on Size and set SIZE of object as Xsize 0 2 Ysize To end Zsize 0 2 Click on Place and set Position of object as Xpos 0 8 Ypos 0 0 Zpos At end Click on General Define Type ANGLED IN Note that the shape and size of the angled in object do not really matter what matters is the size and shape of the area of intersection between it and any blockage which it overlaps In this case the active inlet area will be the outer surface of the BLOCK 1 object which lies within INTAKE Click on Attributes to set the inlet condition Enter 5 0 m s for the velocity in the X direction This is pointing into the BLOCK 1 blockage and so will be treated as an extraction rate In this case the settings for temperature and turbulence do not matter as it is the in cell values which will be convected out Click OK to close the Attributes dialog Click on OK to close the Object Specification Dialogue Box Create the OUTLET object Click on Object New and New Object Change name to OUTLET Click on Size and set SIZE of object as Xsize 0 1 Ysize To end

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    were invented first for most purposes geometrically located patches are to be preferred The reason is that grids are artificial entities necessary for the purpose of perfoming numerical calculations but forming no part of the physical phenomenon which is to be simulated Indeed it is often desirable to perform the simulation with more than one grid using perhaps a coarse grid at first so as to establish the major features of a flow and a succession of finer ones later in order to procure greater accuracy The use of the SPINTO module makes it easy to do so In such a successive refinement operation it would be extremely tiresome to have to change all the IXF IXL etc of the PATCHes each time the grid was changed If geometric locators are used there is no need for this RSET or dot patch Although too little experience has been gained of either of the two methods for a firm recommendation to be made it seems probable that the greater simplicity of the dot patch method will cause it to be preferred 2 The uses of PATCH The uses of PATCH in the four above mentioned Groups will now be described separately 2 a Initial value patches in Group 11 In group 11 the last two arguments are always 1 for the initial values can be set only at time step 1 The PATCH types operative in group 11 are INIVAL LINVLX LINVLY and LINVLZ PATCH in Group 11 is always followed by one or more INIT commands each having four arguments namely patch name variable index or name coefficient and value The INIVAL type An example is PATCH START INIVAL 1 NX 2 1 NY 3 NZ 2 1 1 INIT START U1 0 0 12 5 This because the type is INIVAL will set the initial value of U1 to equal 12 5 if the PIL variable INIADD equals F but if INIADD T the value 12 5 is added to whatever has already been set by FIINIT U1 and by earlier appearing INIT commands If the variable is being stored but not solved as would be the case with porosities for example the value will be retained throughout When porosities eg NPOR fields are being set it is important to remember to put FIINIT NPOR 1 0 so that no blockage is present in sections of the domain not identified by PATCH The LINVLX LINVLY and LINVLZ types If it is desired to give the variable initial values which vary linearly with ix iy or iz the following steps should be taken the PATCH type should be LINVLX LINVLY or LINVLZ the third argument of INIT should be given the value of the multiplier of x y or z ie the gradient the fourth argument of INIT should be given the value of the additive constant i e the value in the first cell INIADD When INIADD is true judicious use of the various types of patches permits complicated initial value variations to be contrived Setting initial values via GROUND For more complicated variations of the initial fields than those provided by the above options the fourth argument of INIT should be set to GRND This causes EARTH to visit group 11 of GROUND for an array of GROUND set VALues for each cell in the PATCH For example PATCH DOMAIN INIVAL 1 NX 1 NY 1 NZ 1 1 INIT DOMAIN H1 0 0 GRND requires the user to provide in group 11 of GROUND a sequence which fills the EARTH array referred to by the index VAL for INDVAR H1 at each IZ slab of the domain INIFLD To check that the initial fields are correctly set the user should set INIFLD T to cause EARTH to print out the initial fields at the beginning of the calculation Uniform velocity fields for BFC grids Uni directional flows can be initialized by means of the special PATCH names starting IBFC that causes group 11 of GREX3 to call subroutine GXBFC The following commands result in a uniform initial flow at 99 0 m s parallel to ZC in a body fitted grid PATCH IBFC INIVAL 1 NX 1 NY 1 NZ 1 1 INIT IBFC1 U1 0 0 GRND1 INIT IBFC1 V1 0 0 GRND1 INIT IBFC1 W1 0 0 GRND1 INIT IBFC1 UCRT 0 0 0 0 INIT IBFC1 VCRT 0 0 0 0 INIT IBFC1 WCRT 0 0 99 0 2 b Term modifying patches in Group 12 PATCH can be used in Group 12 to make local adjustments to the terms in the differential equations The following patch names in which is a wildcard and GP12 can be replaced by an ampersand cause the terms indicated for the variable appearing as the second argument of a corresponding COVAL statement to be multiplied by the third CO argument of that COVAL in the cells occupied by the PATCH Patch name terms affected GP12CON all convection terms GP12SOR all built in source terms GP12CNE east face convection terms GP12CNN north face convection terms GP12CNH high face convection terms GP12DFE east face diffusion terms GP12DFN north face diffusion terms GP12DFH high face diffusion terms For example PATCH GP12CNEW CELL IXF IXL IYF IYL IZF IZL f step l step COVAL GP12CNEW W1 0 0 0 0 COVAL GP12CNEW W2 0 0 0 0 would cut out the east face convection terms for the first and second phase z direction velocity components in the cells and for the duration indicated by arguments 3 to 10 of the PATCH command CONTACT RESISTANCE IN HEAT TRANSFER PROBLEMS Contact resistances can be introduced into heat transfer simulations using GP12DF patches The ability to multiply the total diffusive conductance for a particular variable and a particular patch by the constant appearing as the CO argument of the corresponding COVAL is used In addition the VAL argument is given significance Specifically the resistance to diffusion now becomes equal to resnom VAL CO where resnom

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    large C makes the source term the dominant term in the balance equation for PHI which for large C becomes T C V phiP 0 0 i e a large C has the effect of fixing phiP to V The commands COVAL name PHI 2 E10 V and COVAL name PHI FIXVAL V both have this effect as FIXVAL is numerically equal to 2 0E10 A very small C and a very large V set the source equal to T C V independently of the value of phiP for example thus COVAL name PHI 1 1E 10 1 1E10 flux COVAL name PHI FIXFLU flux has the same effect because the variable FIXFLU as well as being a large number viz 2 0 E10 is also taken by EARTH as a signal multiply flux by 1 FIXFLU when it adds the COVAL term to the source e Pressure and mass flow boundary conditions Mass flow conditions are supplied by way of pressure boundary conditions eg COVAL name P1 Cp Vp sets a mass source inflow is positive T Cp Vp pressP A large coefficient fixes the in cell pressure pressP to Vp a small Cp and a large Vp set a fixed mass flux equal to T Cp Vp The value Vphi of variable PHI convected in to the domain when this mass source is positive is specified by COVAL name PHI Cphi Vphi This gives a total source for PHI equal to T Cphi Vphi phiP T Cp Vp pressP Vphi phiP The first term represents diffusive inflow the second represents convective inflow Usually the diffusive inflow is neglected so Cphi is set to 0 0 but COVAL name PHI ONLYMS Vphi signifies the same thing i e ONLY MaSs flow For cells in which mass outflow occurs i e in which pressP is greater than Vp the second term above is absent in agreement with the upwind convention used for the cell face fluxes generally Thus for outflow the source is T Cphi Vphi phiP The magnitude of Cp needed to fix the pressure may be estimated from the following expression 1 E3 expected flow rate T Vp This gives a relative difference between Vp and the in cell pressure of order 1 E 3 When the pressure is to be fixed to zero as is often done in incompressible flows in which the pressure level is immaterial Vp is omitted from the above expression which then gives an estimate of Cp needed to give an absolute difference between Vp which is 0 0 and pressP of order 1 E 3 A value of Cp 1000 times bigger than that given by the above expression would result in an absolute pressure difference between zero and press P barely representable on a 32 bit machine and should hence be avoided The coefficient FIXP has a numerical value of 1 0 it is suitable for fixing pressures subject to its conformity to the above expression FIXVAL 1 E10 is usually

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    U1 U2 V1 V2 W1 and W2 The sources are provided by coding to be found in open source subroutine GXROTA which resides in file GXROTASO HTM This subroutine is called whenever there exists a PATCH of which the name commences with the characters ROTA whether upper or lower case The patch must be of PHASEM type with CO FIXFLU and VAL GRND1 Options are there provided for cylindrical polar and body fitted coordinates For both coordinate systems the rotational speed in radians per second is set by way of the PIL variable ANGVEL The axis of rotation is defined as follows For body fitted coordinates BFC T The rotation axis is a line defined by two non coincident points A and B having Cartesian coordinates i e XC YC and ZC defined by the PIL variables ROTAXA ROTAYA ROTAZA for point A and ROTAXB ROTAYB ROTAZB for point B COVAL commands should then be specified for all velocity components The PIL commands for a BFC system rotating about the XC axis at 20 radians per second might thus be PATCH ROTA PHASEM 1 NX 1 NY 1 NZ 1 LSTEP COVAL ROTA U1 FIXFLU GRND1 COVAL ROTA V1 FIXFLU GRND1 COVAL ROTA W1 FIXFLU GRND1 ANGVEL 20 0 ROTAXA 0 0 ROTAYA 0 0 ROTAZA 0 0 ROTAXB 1 0 ROTAYB 0 0 ROTAZB 0 0 For cylindrical polar coordinates the axis of rotation is always the z axis i e that for which angle x equals zero and distance y equals minus RINNER Therefore COVAL commands should be specified for U1 U2 and V1 V2 but not for W1 W2 ROTAXA ROTAYA etc need not be set For BFC T it is possible to employ a reduced pressure system This is activated by setting the PIL variable IROTAA 1 its default value is zero This causes the subtraction from the centrifugal force at each location of the force which would be present if the body were rotating as a solid body ie radius ANGVEL 2 When the fluid rotates as a solid body this produces a uniform reduced pressure field In this system the fluid rotates with the grid A wall which is stationary in the absolute frame of reference must be given a velocity with the opposite sign to the fluid If the system is rotating at ANGVEL radians s a wall must be given a velocity of ANGVEL RADIUS The setting IURVAL 1 allows U1 boundary conditions to be set in terms of radians s directly In the VR Editor settings for rotating co ordinate systems are made from the Main Menu Sources panel In cylindrical polar co ordinates it is also possible to create a zone or block of rotating co ordinate system which does not cover the entire domain The cells within this zone are shifted in X by NXDT cells at the start of each time step All SOLVEd and STOREd variables all geometrical quantities and all cut cell values are so shifted

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/rotate.htm (2016-02-15)
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  • In-form7.htm
    in the upper layer of the ocean when a plume of somewhat less dense oil droplet carrying water rises from a tanker wreck on the ocean floor Separate parabolic mode PHOENICS studies of the plume have shown that the plume has an approximately sinusoidal velocity profile and it is therefore this which must be provided as an input to the elliptic upper layer calculation The relevant lines are patch leak low 1 1 1 12 1 1 1 1 source of p1 at leak is 1000 0 03 sin 532 yg 338 7 with fixflu from which it can be deduced that the half width of the sine curve is 532 meters The resulting w1 contours and velocity vectors near the base of the layer can be seen here The contours show that the fluid entering from below quickly changes its direction to horizontal and then downward no doubt because of the influence of the density gradients This case will be referred to again under the heading of momentum sources Injection through a wall Library case 747 illustrates flow in a duct with a porous wall through which additional fluid is injected The injection rate increases linearly with distance along the duct c Momentum sources Inlet velocity profile The cases used for the illustration of mass flow boundary conditions namely 745 746 and 747 illustrate momentum sources also of which the interesting ones are those for U1 the velocity normal to the inlet surface In each case two Z slabs are employed solely in order that alternative means of setting In Form sources for example with or without the COVAL function produce identical results Case 746 is the simplest for the formula of the In Form source statement is simply VELIN with ONLYMS the latter condition signifying that the momentum flux into each cell equals VELIN times the mass flow per unit area The with ONLYMS condition is identical in its action to that of ONLYMS as the third argument of a PIL COVAL command Had the condition not been supplied the formula would have had to be written as RHO1 VELIN 2 Similar remarks are appropriate about cases 745 and 747 Wall friction examples Laminar wall friction is represented in cases 746 745 and 747 In the first case the walls are at rest Therefore the formula is either 0 0 for the patch of SWALL type or 0 0 with LAMWALL for that of NORTH type The COVAL commmand of PIL could express this condition perfectly well but this is not true of case 745 in which the walls are moving at velocities which are proportional to XU the distance along the duct For this In Form s capabilities are needed case 748 An environmental example Library case 401 has already been referred to in respect of mass sources Now the momentum source is considered Inspection of the two lines source of p1 at leak is 1000 0 03 sin 532 yg 338 7 with fixflu source of w1 at leak is 0 03 sin 532 yg 338 7 with onlyms reveals that the formula in the second which represents the momentum source is the same as that in the first apart from the absence of the 1000 0 which represents the density Coupled with the condition with ONLYMS this entails that the momentum flux per unit area is density velocity 2 which is what is required Stirring caused by a paddle Library case 756 illustrates momentum sources which vary with both position and time This is effected by the In Form statements for sources of U1 and V1 PATCH ALL CELL 1 NX 1 NY 1 NZ 1 LSTEP SOURCE of U1 at ALL is 1 E5 VEL YIC YG U1 with IMAT PAD LINE SOURCE of V1 at ALL is 1 E5 VEL XG XIC V1 with IMAT PAD LINE which signify that over the patch named ALL which extends over the whole domain the sources are proportional to the difference between the prevailing velocity at the point and the position dependent quantities VEL YIC YG and VEL XG XIC The constant multiplying the velocity differences has been made large so as to causes U1 and V1 to be close to the desired values The time dependence is brought about by clever use of the STORED keyword which being placed in a DO loop in the Q1 file provides a different distribution of IMAT at the start of each times step This is not the most economical method of simulating a moving object see section 8 for better ones but it well illustrates the power of well chosen In Form statements The condition IMAT PAD signifies that the source is to be applied only to those cells for which the PRPS value IMAT is greater than or equal to PAD the material index of the paddle which happens to be 100 which is greater than the 67 0 signifying water which prevails elsewhwere in the domain Following the delimiter is a second condition namely LINE which is an abbreviation of LINEARISED This is an instruction which requires that the source is introduced in the linearised manner which ensures that it becomes zero when the velocity equals the desired value Without this condition the source would have been created in the fixed flux manner which in COVAL statements is specified by setting FIXFLU as the third argument Frictional resistance In case 709 In Form is used for introducing a frictional resistance at the bottom of a channel In the formulae used VABS stand for the absolute velocity at the centre of the scalar cells 1000 for the presumed fluid velocity and 0 003 for the friction factor which it is desired to introduce Therefore a formula which would be somewhat closer to the evident intention would be for the source of W1 to replace VABS by 0 5 VABS HIGH VABS with a corresponding modification for the source of V1 Such refinements may not have been thought to be worthwhile by the author of the library case but In Form could provide them were they required d Other sources Pressure gradients An interesting use of the In Form source statement is provided by library case 759 which contrives in a very simple manner to provide a solution for the so called co located velocities ie those prevailing at the cell centres for the well known square cavity problem The indexing technique is employed because it is necessary to introduce pressure gradients into the formulae Chemical reaction Case 751 illustrates how In Form can be used for the creation of chemical reaction sources in this case for a reaction rate which depends both on the value of the dependent variable and on the x and y co ordinates A single differential equation is being solved namely that for the reactedness RCTD but a second variable namely RATE is computed for each location it is the volumetric reaction rate It is the distribution of the latter with x and y which is displayed in this contour plot Case 492 illustrates the use of In Form to simulate chemical reaction in a turbulent gas by way of the eddy break up formula Velocity potential and stream function Since the useability of PHOENICS for solving ideal fluid problems is sometimes overlooked cases 126 and 127 may be interesting In Form is used for setting the velocity potential in the former and the stream function in the latter at the boundaries of a domain in which a plate is held at an angle to the stream in which it is immersed The computed velocity vectors for the two cases are shown on line here and here 7 3 Sources for VR objects Contents Syntax Sources of scalar quantities Mass sources Momentum sources Other sources a Syntax Method 1 In Form can set the sources for a VR type object in a manner similar to that used for patches simply replacing the PATCH name by the OBJECT name thus SOURCE of VAR NAME at VR OBJECT NAME is FORMULA The VR OBJECT NAME like a patch name marks the part of the domain inside which the source is to be applied but it does so in geometry related terms by way of lines in the Q1 file starting with OBJ The object describing lines usually appear below the source describing lines in the Q1 file but this is not necessary Method 2 In Form sources for a VR type object can also be set by editing them into the VR section of the Q1 file The source formulas are placed in the lines which describes attributes of VR objects thus OBJ INFSRC VARNAME FORMULA If the length of a line exceeds 68 symbols then the formula continuation is recorded in the next line as follows OBJ INFSRC VARNAME FORMULA BEGINNING OBJ INFSRC VARNAME FORMULA CONTINUATION SOURCE it should be mentioned is not the only In Form keyword which can be treated by this second method Thus INFINI INFSTO INFST1 and INFMAK have the same effects as the In Form statements starting INITIAL STORED STORE1 and MAKE The In Form object defining lines may be written to the Q1 file by way of any word processor Also the In Form object defining expressions can be located in DAT or POB files In this case SATELLITE reads them from these files and places them appropriately in the Q1 file Examples of both methods will now be described b Sources of scalar quantities Heat sources Case v146 exemplifies the use of Method 1 to set a heat source in a single rod as described here However that use is de activated in favour of Method 2 as is shown here The two methods produce precisely the same solutions with the trivial difference that that the SPEDATs echoed into Group 19 of the RESULT file appear in slightly different orders Case v147 exemplifies the use of Method 1 and Method 2 to set heat sources in an array of rods as described here Turbulence quantity sources Case 658 exemplifies the use of In Form for creating sources of turbulence quantities in a boundary layer the VR object in question being the one called INLET Clearly it is convenient to express all the sources for that object by means of formulae containing assignable quantities namely the character variables VIN and MDOT Chemical composition sources Case 733 exemplifies the use of In Form for creating sources of a chemical reactant in this case the rate being proportional to the energy dissipation time constant EP KE and to the negative of the fuel concentration The ability swiftly to implement new expressions for the reaction rate is especially valued by combustion scientists who are forever searching for ways to reduced the observed phenomena to order c Mass sources Inlet objects Case 658 already cited in respect of turbulence quantities serves again to exemplify mass sources at inlets Further comment appears not be needed c Momentum sources Inlet objects Fan objects d Other sources 7 4 Sources for In Form objects Contents Syntax Sources of scalar quantities Mass sources Momentum sources Other sources a Syntax All that it is necessary to read about In Form objects in general has been written already in section 6 4 above in connection with initial value setting It is necessary to add at this point only that the syntax for attaching sources to such objects is similar to that for initial objects as will now be illustrated b Sources of scalar quantities Heat sources Library case 768 illustrates a method creating and adding a heat source to a spiral shaped In Form object in a cylindrical polar co ordinate system The required shape In order to create the required shape which is shown here by displaying the surface of the marker variable MARK the drilling technique is employed That is to say that a sphere of constant radius is moved along a spiral trajectory in order to mark the cells through which it passes The set of marked cells comprises the In Form object A single coil spiral can be formed from a ring by cutting it and moving the severed ends in an axial direction In this case a two loop spiral is required Creating a ring To create a ring shaped In Form object it suffices to define the X and Y co ordinates of the sphere centre as follows SPHERE 10 0 5 sin xg 1 0 0 5 cos xg 1 0 0 2 Here the 1 0s represent the co ordinates of the origin of the polar co ordinate system 0 5 is the radius of the centre line circle of the ring along which the sphere is to move 0 2 is the radius of the circular cross section of the ring and xg is current X polar co ordinate of cell centre in radians at the particular iz index of the slab for which the values of MARK are being computed The Z co ordinate will constant and equal to 1 0 Creating the first coil of the spiral To create an In Form object with spiral shape the Z co ordinate should be made to depend linearly on the angular co ordinate xg for example 1 0 0 5 xg where 1 0 is the Z co ordinate of the start point of the spiral The Z co ordinate of the final point of the spiral will be 1 0 5 XULAST 1 0 5 6 28 4 13 The complete In Form statement will thus be INFOB at PATCH1 is SPHERE 1 0 0 5 sin xg 1 0 0 5 cos xg 1 0 0 5 xg 0 2 with INFOB 1 Creating the second coil of the spiral An additional In Form statement is required for creation of the second spiral coil In order that they should be connected without a break the Z co ordinate of the starting point of the second coil should be equal to the Z co ordinate of the final point of the first coil Thus the Z co ordinate should be calculated by the next formula 4 14 0 5 xg The two coil spiral Thus the In Form object with shape of the spiral with two coils can be created by following two In Form statements INFOB at PATCH1 is SPHERE 1 0 0 5 sin xg 1 0 0 5 cos xg 1 0 0 5 xg 0 2 with INFOB 1 INFOB at PATCH1 is SPHERE 1 0 0 5 sin xg 1 0 0 5 cos xg 4 14 0 5 xg 0 2 with INFOB 1 Moreover they can be incorporated into one statement namely INFOB at PATCH1 is SPHERE 1 0 0 5 sin xg 1 0 5 cos xg 1 0 0 5 xg 0 2 SPHERE 1 0 0 5 sin xg 1 0 0 5 cos xg 4 14 0 5 xg 0 2 with INFOB 1 One object or two Lest the above description should have given a different impression it should be emphasised that even when two In Form statements are used there is still only one object namely INFOB 1 This would still be true if the formulae in the second statement had been different from those in the first describing a straight cylinder rather than a continuation of the coil Setting the heat source In comparison with the actions necessary to create the object and the number of words needed to describe them those concerned with the setting of the heat source are much fewer In library case 768 a constant source of 2 0 kilowatts is provided thus SOURCE of TEM1 at PATCH1 is 2000 with INFOB 1 However any formula recognised by In Form could be provided It should be noted that at PATCH1 appears not at INFOB 1 In effect the In Form object is acting as a qualifier indicating into which cells of PATCH1 the source is to be provided This observation answers any question about the type of the source for the type is dictated by the second argument of the the PATCH specification which in library case 768 is CELL This information immediately raises a further question namely how many cells does the drilling sphere actually mark One way of finding out would be to use the In Form SUM feature to compute the total amount of the MARK quantity in the patch but no exemplification of this idea yet exists However a solution to a similar problem will be discussed below in connection with the mass flow sources of library case 785 If that example were followed in the present case the actions could be Recognise that probably the choice of CELL as the patch type was ill advised Change it to VOLUME Calculate the true volume of the spiral and the total heat that is to be supplied Then specify that amount times a correction factor as that which is to be specified in the source statement Determine the magnitude of that factor which will differ according to the fineness of the grid by using MAKE and STORE1 so as to calculate once only the ratio between the total volume of all the heat supplying cells and the actual volume of the spiral c Mass sources Inlet objects Library case 785 introduces a gas in flow boundary condition by means of an In Form object It is of the kind commonly found in combustion equipment consisting of a circular aperture in a plane domain boundary with a concentric annular aperture around it Click here to see the MARK contours which clearly show the geometry of the inlets and their relation the the grid Because In Form objects know nothing of partially blocked cells and regard each cell which they touch as wholly inside or wholly outside them the edges of the inner and outer radii of the annulus

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/in-form7.htm (2016-02-15)
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  • In-form5.htm
    plume displayed by way of velocity vectors the almost invisible contours of the oil concentration oil and the much more visible contours of log10 oil If however the logarithm of the concentration has been computed its variation being less extreme is easier to display Control of when and where the quantities are computed The STORED command formula can be optionally followed by with condition where condition is one of ZSLSTR for start of z slab ZSLFIN for finish of z slab SWPSTR for start of sweep SWPFIN for finish of sweep TSTSTR for start of time step TSTFIN for finish of time step These may be understood by recalling that PHOENICS calculations are organised in nested iterative loops whereby the innermost loop visits all the cells in a slab of constant IZ the intermediate loop sweeps through the whole domain thereby visiting every slab and the outermost loop if the phenomenon simulated is time dependent updates variables at each time step These with conditions act as economy devices enabling values to be updated only when needed If no condition is supplied In Form takes ZSLFIN as its default Inspection of the Q1 for case 805 will show that with SWPFIN was used 5 2 Whole field for participation in the calculation Auxiliary variables may be stored whole field and computed within the main equation solving loop for many purposes including those of acting as intermediaries in the calculation of sources or fluid properties Examples of use Thus The following lines extracted from the core library case 701 Temperature STORED of T1 is H1 CP Heat capacity STORED of CP is 4186 8 POL3 T1 616 0040428 1 8333e 5 2 38E 08 enable the stored only temperature T1 to be computed from the solved for enthalpy Here it should be noted that the calculation of T1 makes use of CP and that of CP makes use of T1 Divergence is a possibility in such cases but it does not arise in this case because the dependence of CP on T1 is small Inspection of the Q1 file shows that the so calculated T1 is used extensively for further property calculations In case 706 the lines STORED VAR FLIQ IS MAX 1 e 5 MIN 1 TEMP RG 1 RG 2 RG 1 PATCH iMUSHY VOLUME 1 NX 1 NY 1 NZ 1 1 SOURCE OF U1 AT iMUSHY IS 0 U1 RG 3 1 FLIQ FLIQ SOURCE OF V1 AT iMUSHY IS 0 V1 RG 3 1 FLIQ FLIQ enable the liquid fraction to be deduced from the temperature during the casting of a metal alloy and thereafter the momentum sinks to be computed In case 752 STORED of DM is 1 AM BM CM EM deduces the concentration of a fifth not solved for concentration DM to be computed from the solved for values of the four other components of a mixture This it should be remarked as a display only action for DM appears not to be used

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/in-form5.htm (2016-02-15)
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