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  • ENC_PIL7.HTM
    in PIL DO LOOPS IF THEN ELSE constructs CASE statements LOOPS SUBROUTINES GOTO Statements Error Trapping Output to the VDU READVDU Graphics Primitives The way in which PIL is used in practice is best seen by inspection of files in the PHOENICS Input Library The use of the search facility of the PHOENICS Commander makes it easy to find examples A library case which is especially rich in use of

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/enc_pil7.htm (2016-02-15)
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  • PRELUDE Tutorial BEGIN1
    out 0 55 will appear to the right of the space and the z dimension of the drawn image will change correspondingly Now change xsize to 1 2 The three size dimensions of the domain box to the right of the white spaces are now 1 2 1 2 and 0 6 They have all changed together and you have seen your first demonstration of the relational capabilities of PRELUDE Method 5 Introducing functions You may have noticed that when you placed the cursor in one of the white boxes for the first time three boxes labelled Function Object Name and Insert Function appeared beneath the toolbar Use of these which is by no means essential for the beginner enables settings to be made by way of click cut and paste operations instead of typing Clicking on the first of these and pointing to X with the mouse cursor reveals this This is a list of x related functions which may be used in expressions once an object name has been selected as their argument Suppose that it is desired to place in the zsize box the expression ysize DOMAIN without having to type the characters This involves using ysize as the function and DOMAIN as the object name To do so first place the cursor in the zsize white space and high light its contents by double clicking as though you were about to type over it Then click on y in the functions drop down menu and then ysize You have now indicated which function you wish to use Next click on DOMAIN in the Object Name menu thus selecting this as argument Finally click on the Insert Function button Then the desired Ysize DOMAIN will appear in the Zsize white space Click on any other space then observe that the right hand number and the y dimension of the domain box in the drawn image change appropriately It should be noted that the right click trick i e recovering earlier values see Method 2 works in the same way for expressions as it does for numbers To check this right click in the zsize space You will see Method 6 Introducing new variables and or expressions To learn about this method click on the box marked Functions in the menu bar at the top of the graphics window You will then see the following Replace newname by say dimension press OK then click on the down arrow beside the left hand box and select the variable type real In the same way introduce the real variables length width and height Your screen should now look like this By default the newly introduced functions are set to zero It is now time to fill these boxes with some meaningful data for example as follows Type 1 1 instead of 0 in the dimension space Double click on the white space opposite length and then on the word dimension in the functions list Do the same for the width and height boxes Now highlight the 1 1 in the xsize box of the DOMAIN attributes Click on LENGTH in the functions list and see it appear in the white space Make the corresponding actions so as to ensure that WIDTH and HEIGHT appear in the other two spaces Your screen should now look like this Finally click on the Graphics tab and the familiar graphics window will appear with the Size tab open You should there see that the domain sizes in the boxes are specified parametrically by LENGTH WIDTH and HEIGHT respectively and their true values are given to the right of each size box Being now at the end of this long section of the tutorial you should bear in mind two things You have learned by concentrating exhaustively on a single aspect of data input things about PRELUDE input generally It will not therefore be necessary to go into such detail in later tutorials Although the tutorial has shown you things which you could do that does not mean that PRELUDE forces you to do any of them Do not therefore suppose that the practical use of PRELUDE will be laborious It is not Let us now examine other objects in the scenario provided by the beginner gateway First so as to make an entirely clean start close PRELUDE by clicking on the top right hand white cross in its red box Now re start PRELUDE set the casename to be tut 1a say and re load the beginner gateway Click on the tree icon and this time click also on the next to DOMAIN and then on the close to AXES You should then see Evidently the DOMAIN has several children dependent on it and one of them called AXES has three children of its own 5 2 The clipper object First select CLIPPER by clicking on it or on its name in the tree Its three perpendicular planes will then be outlined in white which is not easy to see unless the back ground colour is different from white Such outlining is carried out for every object that is selected except in the case of the domain which is special in several ways Changing the size Now click the red tick icon in the toolbar You should then be presented with a greater number of buttons than for DOMAIN as shown here First click on Size then by clicking on the up and down arrows or by typing entries into the white boxes confirm that the x y and z dimensions can be changed in the same manner as before to get a picture like this However CLIPPER and all other objects which you will later introduce also allow rotation and changes of position relative to the domain as you are now invited to investigate Rotating an object Click now on Rots then click and hold one of the up and down arrows to the right of Xrot Yrot and Zrot The object will

    Original URL path: http://www.cham.co.uk/phoenics/d_prelud/gateways/beginner/d_tuts/begin1.htm (2016-02-15)
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  • PRELUDE Tutorial begin2
    2 or any other character string but WITHOUT BLANK SPACES Click on Load Gateway and then select Beginner to see in the Graphics window the domain limited by a red outlined box and its co ordinate system with the origin placed in the bottom distant corner of the domain Click on the object tree icon in the toolbar to display all objects inside the domain Why are the co ordinate system axes displayed in such a way Z axis is directed upwards X axis points to the left and Y axis to the right Is it the only possible way to represent the axes object The answers to both questions can be obtained through the Right Hand Rule The default representation of the co ordinate system in PHOENICS parlance is the Right Hand one according to the following picture It signifies that the index finger of the right hand points to Z direction the thumb to Y and the middle finger points to X However it is true only if the observer s eye is in front of this picture and distanced from the origin The role of the observer s eye is played here by the object which is called CAMERA0 Let us discuss how the the co ordinate system representation will vary with the CAMERA0 position Check that the CAMERA0 object is selected in the object tree the sign of this are the words Selected CAMERA0 Attached to Domain in the top right part of the graphics window Otherwise first click on CAMERA0 in the object tree Click on on the red tick icon to reveal its attributes mainly its position As you can see to have such representation of the co ordinate system co ordinates of the point where the CAMERA0 object should be placed although dependent

    Original URL path: http://www.cham.co.uk/phoenics/d_prelud/gateways/beginner/d_tuts/begin2.htm (2016-02-15)
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  • PRELUDE Tutorial VWT1sa, Simulating flow around a simple object
    tutorial 1 but then return them to their original values before proceeding However you can add other parameters affecting the flow around a body in the wind tunnel choosing them from the Add Parameter box It might be hidden in this case enlarge the Attributes window by dragging its handle down Click on the right arrow to open the following drop down menu Select from that list any parameter you are specifically interested in and would like to control say pressure Make sure that it has now appeared in your list of parameters and you can now edit it pressing the right arrow and selecting pressure from the Parameters box Investigate the attributes of OUTLET in the same way as you did for INLET namely by displaying the object tree selecting i e clicking on OUTLET selecting Attributes adding a certain parameter apart from pressure from the Add Parameter box revealing the pull down menu of the middle left hand box Pressure has been introduced by default Its panel contains a white box in which the 0 0 signifies that the outlet is being represented as a region where the air pressure is fixed to zero not absolute of course but relative the air is being taken as incompressible therefore any constant value could be chosen Please note that the solid which has been placed into the virtual wind tunnel can be replaced by some other body You can choose it from the store cupboard a folder where objects of different shape are stored To access the store cupboard click on an empty space in the graphic window You will then see the following in the top part of the window opened Click on the store cupboard tab and you will see which objects such as the following which you can place in the VWT i e the Virtual Wind Tunnel What you will in fact see depends on what files having dat 3ds stl extensions are currently in your gateways vwt folder We do not recommend that you change the object now you can experiment later and then run PHOENICS with different objects placed in the VWT However the wind tunnel setting tab is probably worth discussing The next picture shows how it looks like The initial velocity is here set by a parameter windspeed Initially it is equal to 2 m s as was found out when we discussed the inlet velocity and as the number to right of the box shows You can change it entering a new value in place of windspeed in the Speed box You can as well tilt the body inside the VWT specifying the angle of attack For example the body will be put upside down when the angle of attack is 180 degrees but not in case with the sphere Apart from the green sphere representing the point of the coordinate system origin you will see another this time red sphere object This is called monitor and it marks the position

    Original URL path: http://www.cham.co.uk/phoenics/d_prelud/gateways/vwt/d_tuts/vwt1sa.htm (2016-02-15)
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  • PRELUDE Tutorial VWT2SA, Simulating flow around a simple object
    the graphics window Click on the icon in the toolbar to make the object tree visible expand the vtkphi clicking on its sign and select cplane i e the plane where the results of simulation will be displayed Click on the object properties button then on Scalar Properties tab to be sure that the variable to be plotted is pressure Then click on the Cutplane tab and display pressure contours on y plane selecting the corresponding box The symmetry of the test item shape about the constant Y plane coming through its center has resulted in the symmetry of the results obtained This property enables the calculation time to be reduced by making flow simulation around one half of the test item only Switch off the displayed contours clicking on the None box in y direction Select the DOMAIN object in the object tree click on the red tick icon in the tool bar to show its attributes then click on the Size tab It will result in the picture like this The domain sizes depend on the test item sizes more precisely on its radius To ascertain that the test item sizes are the same in every direction select it in the object tree and open the Size tab for the sphere The sphere has the same size along every coordinate axis as it should equal to 1m Select the DOMAIN object once again in the object tree Now we need to reduce the calculation domain by one half in Y direction by typing in the Ysize box what is shown in the picture The domain has become narrower in Y direction The next step to fulfill is to place the test item exactly in the same position in Y direction of the changed domain Select testitem by clicking on it either in the object tree or on the graphics screen Then open the Pos tab The position attributes of the test item in the modified domain are as follows The Y co ordinate of its center YPar mid is located exactly in the domain center in Y direction To have the same Y position of the test item we need to remove its half from the domain i e to increase its Ypos twice to result in the picture like this Rotate the picture with the mouse left button to have a better view of the test item one half of which is now inside and the other outside of the calculation domain Now run the Solver clicking on Options then on Run Solver and after that repeat all the other steps of your first run In the VR Viewer window we advice you to display the same image pressure contours on a constant y plane to permit comparison of the results obtained However it is first necessary to place the cutplane in the same position as it was before The cutplane position is shown by the VTK probe i e by the white tetrahedron before the sphere

    Original URL path: http://www.cham.co.uk/phoenics/d_prelud/gateways/vwt/d_tuts/vwt2sa.htm (2016-02-15)
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  • PRELUDE Tutorial VWT 1
    by displaying the object tree selecting i e clicking on OUTLET selecting Attributes adding a certain parameter apart from pressure from the Add Parameter box revealing the pull down menu of the middle left hand box Pressure has been introduced by default Its panel contains a white box in which the 0 0 signifies that the outlet is being represented as a region where the air pressure is fixed to zero not absolute of course but relative the air is being taken as incompressible therefore any constant value could be chosen Please note that the solid which has been placed into the virtual wind tunnel can be replaced by some other body You can choose it from the store cupboard a folder where objects of different shape are stored To access the store cupboard click on an empty space in the graphic window You will then see the following in the top part of the window opened Click on the store cupboard tab and you will see which objects you can place in the VWT i e the Virtual Wind Tunnel We do not recommend that you change the object now you can experiment later and then run Phoenics with different objects placed in the VWT However the wind tunnel setting tab is probably worth discussing The next picture shows how it looks like The initial velocity is here set by a parameter windspeed Initially it is equal to 2 m s as was found out when we discussed the inlet velocity You can change it entering a new value in place of windspeed in the Speed box You can as well tilt the body inside the VWT specifying the angle of attack For example the body will be put upside down when the angle of attack is 180 degrees but not in case with the sphere Apart from the green sphere representing the point of the coordinate system origin you will see another green sphere object This is called monitor and it marks the position for which spot values are displayed on the graphical monitor when the Solver is making a run We shall return to this point later having started the simulation process 3 Making the simulation Click on Options in the Menu bar and then on Run Solver Then in quick succession you will see evidence on the screen of the running of the PHOENICS Pre Processor module SATELLITE in non interactive mode while it processes the information provided for it by PRELUDE the activation and running of the PHOENICS Solver Module EARTH while it processes the information which it has received from SATELLITE after some time when the computation is finished the initial picture with the Graphics window will be visible on the screen To analyze the convergence you can open the file with the course of computation plots gxmoni gif from your working directory that looks as follows To those interested in such matters it may here be remarked that the downward profile of the curves in the left hand panel shows that the corrections to the solved for variables diminish to very small values as the calculation proceeds the downward trend of the curves in the right hand panel explains the reason the errors i e imbalances in the equations being solved are also diminishing The values in the right hand panel are calculated for the MONITOR we spoke about In pricipal any point inside the DOMAIN can be specified as a MONITOR and flattening of curves for variables at this point is a sign that a certain accuracy of the solution has been achieved it is these imbalances in units say of kg s or joules per second which cause the PHOENICS solver module to make the corrections e g of pressure or temperature In CFD parlance these curves show that the calculation has satisfactorily converged 4 Inspecting the results After the calculation is finished the user is again taken to the Prelude Graphics window to explore the results obtained It was already mentioned in the beginning that two modules could be used for this purpose Prelude itself and the Veiwer Let us try the Viewer first 4 1 by means of the VR Viewer Go to Options Run VR Viewer You will see the image shown here Now click on OK This will result in the following picture in which will be recognised the object the tunnel and the inlet and outlet which you last saw in the graphics window of PRELUDE How to use the PHOENICS Viewer package is a large subject for which separate tutorials exist A useful introduction can be found in the on line document TR324 Nevertheless the following suggestions are made to the newcomer to PHOENICS who wishes to see immediate evidence that he or she has performed a CFD calculation Click the icon which selects contour plotting Click the Y button to select contours on constant y planes Click and hold one of the probe position arrows to the right of the y box until the plotting plane is in the middle of the tunnel This will show a picture with maximum colour contrast like this Clearly evident is the higher pressure region on the left of the object and the lower pressure region on the right Now toggle contours off by clicking on again then click on the Object management button so as to reveal the Object Management panel Select i e click on TESTITEM then click on Action and then on Surface Contours and finally on the X sign in the top right hand corner of the Object Management panel to close it The surface of the object will now be coloured so as to reveal the distribution of pressure over it as shown here When the bottom right mouse button is depressed you can look at the scene from various angles by clicking and holding the left mouse button and then moving the cursor over the screen Lastly observe what happens when you

    Original URL path: http://www.cham.co.uk/phoenics/d_prelud/gateways/vwt/d_tuts/vwt1.htm (2016-02-15)
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  • vwt2.htm
    earlier picture showing the present contents of the store cupboad we know that this information is stored in C phoenics d prelud gateways vwt That is how its contents looks like in part when opened in the Windows environment in thumbnail mode Each object is presented by two files a graphical JPG file where the image is stored and a text DAT file with the numerical information about its shape To introduce new objects to this folder we need simply to place there the corresponding JPG and DAT files Where can you find these files As a matter of fact this is not difficult You will not be forced to create these files as PHOENICS already has lots of objects presented in this form They are stored in C phoenics d satell D OBJECT PUBLIC Examine the sub folders and you may find objects which might be of interest for simulation Let us open the EQUIPMT sub folder and select files for the airfoil object which is often placed in the tunnel for simulation Copy the selected files to C phoenics d prelud gateways vwt Restart Prelude and open the VWT Gateway Click on an empty space in the graphic window and then on the red tick icon in the tool bar Open the store cupboard clicking on the store cupboard tab You will see the objects and find out the the airfoil is already there Experiment with adding other objects to the store cupboard and placing them thereafter into the virtual wind tunnel However do not forget to restore the sphere object in the end as all that follows will be connected with flow simulation around the sphere 5 Making the simulation Click on Options in the Menu bar and then on Run Solver Then in quick succession you will see evidence on the screen of the running of the PHOENICS Pre Processor module SATELLITE in non interactive mode while it processes the information provided for it by PRELUDE the activation and running of the PHOENICS Solver Module EARTH while it processes the information which it has received from SATELLITE the drawing of already familiar computation plots which appear when the computation is finished thus To those interested in such matters it may here be remarked that The curves in the left hand panel represent the maximum values of each of the solved for variables to be found anywhere in the domain those in the right hand panel show their minimum values Which curve corresponds to which variable This can be established by comparing their colors with those used for printing the names of the variables P1 U1 V1 W1 TEM1 in the central column in the lower part of the screen Other columns of interest are those headed Dom Max and Dom Min which contain the actual values of those quantities at the end of the run and the columns headed Change immediately to the right of them which represent their changes in value between the last but

    Original URL path: http://www.cham.co.uk/phoenics/d_prelud/gateways/vwt/d_tuts/vwt2.htm (2016-02-15)
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  • vwt3.htm
    to show its attributes It will result in the picture like this The domain sizes depend on the test item x size Now we need to reduce the calculation domain by one half in Y direction by typing 1 in the Ysize box as is shown in the picture The next step to fulfill is to place the test item exactly in the same position in Y direction of the changed domain Select the test item clicking on it either in the object tree or on the graphisc screen Then open the Pos tab The position attributes of the test item in the modified domain are as follows The Y co ordinate of its center YPar mid is located exactly in the domain center in Y direction To have the same Y position of the test item we need to remove its half from the domain i e to increase its Ypos twice simply typing 1 the Ypos box to result in the picture like this Rotate the picture with the mouse left button to have a better view of the test item one half of which is now inside and the other outside of the calculation domain Now run the Solver clicking on Options then on Run Solver and after that repeat all the other steps of your first run In the VR Viewer window we advice you to display the same image pressure contours on a constant Z plane to permit comparison of the results obtained As you can see only one half of the test item has been simulated and the results of your second run are in good agreement with those of the first one Let us now close the VR Viewer window and return to the Prelude Editor At the very bottom of the opened tab with the result file you will see the following Comparing the calculation time of 9 seconds with the previous 16 seconds we may establish the fact of actual reduction of the calculation time when flows around symmetrical bodies are simulated 3 Saving the results The results of your PHOENICS runs will all be found in your working folder where they will remain until deleted or removed by you or over written by later runs with the same case name However you can save the settings which you made during your Prelude session if you wish to return to this case later In the Prelude Editor window click the File button of the menu bar and then on Save Q3 If for some reason you did not give a specific name for this case or did not create a specific folder for it you may do all these now using the Save Q3 as command of the File menu This command allows your settings to be saved and stored in any existing folder or in a new one if you will create it 4 Making a simulation for the sphere test item Let us now return to the case that

    Original URL path: http://www.cham.co.uk/phoenics/d_prelud/gateways/vwt/d_tuts/vwt3.htm (2016-02-15)
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web-archive-uk.com, 2017-12-13