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    not included explicitly in the Q1 file seen above NZ 20 indicates that the computational grid has 20 subdivisions in the z direction ZWLAST 0 2 indicates that the z direction length of domain of interest is 0 2 meters S I units being presumed in the absence of other information The ZFRAC array values indicate the fractions of the total z direction length at which the grid cells have their walls All the entries except the first are the consequences of the command seen in Group 5 of the input file namely GRDPWR Z 20 0 20 1 0 To understand how this came about the reader would have to consult the GRDPWR entry of the help file gt Two further examples will now be shown of what can be SEEn namely the consequences of SEE 9 which throws light on fluid property settings and SEE 15 which reveals some of the solution control settings The first which corresponds to the commands under the GROUP 9 comment in the library file elicits VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV The second which corresponds to entries below GROUP 15 in the library file yields VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV Data settings of the above groups are among those which it will prove interesting to alter Attention will now be devoted to describing the first way of making alterations 6 Direct setting of data gt Suppose that it is desired to give the run a new title e g MY FIRST RUN Then the TEXT command should be used by typing TEXT MY FIRST RUN and SEE 1 will now yield VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV Next suppose that it is desired to increase the fluid density RHO1 from its default value of 1 0 to say 4 967 Then the following should be typed at the keyboard RHO1 4 967 whereupon SEE 9 will yield VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV Finally let it be supposed that it is desired to change one of the residual reference in proportion to RHO1 by typing RESREF P1 RESREF P1 RHO1 and to check its efficacy by way of SEE 15 Then the information coming to the screen would be VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV which shows that the change has indeed been effected gt From the last example it will be seen that it is possible to make one change depend upon another However care is needed if the PHOENICS user decided to change RHO1 back again RESREF P1 would not be automatically restored at the same time because all commands are acted upon immediately There is a way to ensure that interdependent variables all change in correspondence but it requires the use the EDITOR mode which will be described in section 7 7 Viewing the instruction stack gt The instructions which were entered at the keyboard have not been erased as soon as acted upon instead they have been added on to the bottom of the instruction stack which at first contained only what was supplied by the LOADing of the library file This instruction stack can be viewed by using the built in editing facilities of the PHOENICS satellite as will now be illustrated gt No special command is necessary for entry into the editing mode its facilities are always on call However it may be useful just before they are employed to receive a reminder of what they are This is effected by typing EDITOR with the following consequential print out on the screen VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV gt Some of the commands will now be employed starting with LB which results in VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV This confirms that the alteration of the RESREF P1 value is indeed the last command in the instruction stack Where it lies in relation to the preceding commands can be seen from the upwards list shown by the LB command The prior entries using the TEXT command and setting RHO1 are also shown gt It should be noted that the editor has added line numbers to the instructions for ease of reference gt Suppose that the resetting RHO1 1 0 is now made and followed by L64 68 The bottom of the stack now appears as VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV wherefrom it is easily seen that the RESREF P1 value will correspond with 4 967 not with 1 0 What was wanted therefore was not the addition of an instruction at the bottom line 68 but rather the replacement of line 66 This can be effected by typing R66 with the result VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV whereupon RHO1 1 0 is typed in There follows VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV again which means that the editor awaits further editing commands D68 is appropriate now because 0 line 68 is redundant and pressing the return key on the appearance of the next INSERT EDITS message signals that the editing is over for the time being If now LB is entered the screen will show VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV gt If at this stage the PHOENICS user types SEE 15 he will find possibly to his surprise and disappointment that RESREF P1 still equals 4 967E 06 The reason is that although the instruction stack has been modified the PHOENICS satellite has not been told to go back to the top and interpret it all over again The command which has this effect is LOAD STACK If SEE 15 is typed thereafter RESREF P1 will at last be found to have the correct value gt It is especially desirable to use the editor rather than direct setting of data items when it is the fineness of the grid which is being changed for example when NZ is to be increased from 20 to 25 Thus the direct setting NZ 25 followed by SEE 5 will lead to VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV This will cause the PHOENICS EARTH run to fail because NZ has been set to 25 successfully but still only 20 values of ZFRAC have been provided Viewing the instruction stack shows via LT VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV or via L12 15 VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV 12 GROUP 4 Y direction grid specification 13 GRDPWR Y 20 0 01 1 0 14 GROUP 5 Z direction grid specification 15 GRDPWR Z 20 0 20

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_tuts/input.htm (2016-02-15)
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  • 0 000E 00 1 000E 01 The contour plot for C and those for B and A which follow confirm that substances with high Prandtl Schmidt numbers diffuse less fast than those with low ones VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV CONTOUR PLOT OF B VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV CONTOUR PLOT OF A Changing the print out of spot values and residuals It was promised above that the plots of spot values and residual sums would be modified in appearance The first modification involves editing the instruction stack for case 244 248 An L57 command followed by an LC command reveals that the author of the case set NPLT to 1 VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV L57 57 NYPRIN 2 NZPRIN 5 NPLT 1 Use of the command R56 allows the line to be modified to NYPRIN 2 NZPRIN 5 Reinterpretation of the instruction stack causes NPLT to assume its default value of 1 which is quickly ascertained by typing NPLT VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV NPLT 1 Execution of an EARTH run and analysis of the RESULT file shows that the plots for spot values and residuals have indeed changed The default setting for NPLT gives rather infrequent values in the plots for spot values and residuals VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV SPOT VALUES VS SWEEP ITHYD IF PARAB VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV RESIDUALS VS SWEEP ITHYD IF PARAB The author of the Q1 file probably made a wise decision in his selection of the original value for NPLT NPLT will now be reset to 1 for the next run however attention will be focussed on the last 10 sweeps in the solution sequence by resetting the variable IPLTF which is the first sweep number for which plots will be produced IPLTF formerly at its default value of 1 will now be set to 11 so that the spot values and residual sums will be printed only for the last ten sweeps The opportunity will be taken to exhibit two further print out controls namely ITABL and ORSIZ These will be set to 3 and 0 4 respectively The first causes tables of numbers to be printed in addition to the plots and the second doubles the vertical scale of the plots The help facility should be consulted for further information about these and other GROUP 23 controls The relevant part of the RESULT file thereupon becomes VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV SPOT VALUES VS SWEEP ITHYD IF PARAB VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV 1 00 P B B H A A C C It can now be seen that changes are still taking place in the spot values during the last ten sweeps but they are small VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV TABULATION OF ABSCISSA AND ORDINATES The table and the plot confirm the generally downward trend of the residuals It should be mentioned that the printing and or tabulation of spot values and or residuals can be controlled variable by variable by means of the last two arguments of the OUTPUT command This is explained along with other matters in the help entry for OUTPUT which is VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV OUTPUT OUTPUT Changing the print out to the screen The frequency in terms of number of sweeps with which the imbalances in the equations are transmitted to the VDU is controlled by the value of the variable TSTSWP for which the help file entry is VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV TSTSWP TSTSWP Print out for a particular variable can be suppressed altogether by the setting of its RESREF to 0 0 Thus if TSTSWP is set equal to 5 and RESREF P1 is set equal to 0 0 the first print out of imbalances to reach the screen is VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV TIME STEP 1 SWEEP 5 This should be compared with the screen output which would have been obtained without these settings of RESREF and TSTSWP VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV TIME STEP 1 SWEEP 1 As indicated by the help entry for OUTPUT reproduced at the end of the previous section the residuals print out can also be suppressed for a particular variable by entering N as the fifth argument i e the fourth yes or no slot of the OUTPUT command It is indeed better to do this than to set RESREF equal to zero for it allows RESREF still to enter into the decision about when iterations or sweeps should be terminated The use of RESTRT or AUTOPS Because it was desired to change the print out relating to the whole run the changes discussed in sections 2 and 3 necessarily involved repeating the run This was not troublesome because the execution time was so small When the print out requirements relate only to final values however there is no necessity to repeat the whole calculation instead one can simply make either a restart or an autopsy run merely by changing the print out control settings in the Q1 file Restarts are effected by setting RESTRT ALL and LSWEEP 2 in the Q1 file When EARTH execution starts the message on the VDU screen on the presumption that the last mentioned TSTSWP and RESREF P1 changes have been undone is VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV GROUND STATION IS GROUND FTN 11 10 86 Thus one further sweep has been performed starting from where the previous run left off so that the residuals remain small This was possible because the PIL variable SAVE equalled T its default value in the previous run so that the fields stored on PHIDA could be picked up Restarts are mainly useful when an exploratory calculation is being carried out for which the PHOENICS user is certain at the start neither of the total number of print outs that he will require nor of such other settings as numbers of sweeps and iterations and values of relaxation parameters However if it is only the print out about which he is uncertain he can make use of the special kind of restart known as an autopsy run This is effected by the Q1 command AUTOPS T RESTRT ALL as the help entry for AUTOPS explains VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV AUTOPS AUTOPS When EARTH is again executed the message to the screen is now VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV INITIAL FIELDS READ FROM PHIDA which differs in that all

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