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FLOWCast UNIT 1: Overview and Quick Start Guide

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Q: What is FLOWCast ?

A: FLOWCast is the fluid flow modeling module for mold filling simulation, which works in conjunction with the SOLIDCast modeling system. FLOWCast was developed using flow simulation technology from Altair Engineering, Inc. and is a joint product of Altair Engineering and Finite Solutions.

The FLOWCast module must be purchased separately. After purchasing and installing FLOWCast, you will need to send FLOWCast System Codes to Finite Solutions, Inc. and receive Response Codes to activate the program.


Q: What can FLOWCast do?

A: FLOWCast simulates the flow of liquid metal into a mold, along with the cooling of the metal and the heating of the mold. FLOWCast has two modes :


Quick Simulation
: This is a fast-filling algorithm, which is not full CFD, but uses a cascade type of fill simulation to quickly fill a mold. The Quick Simulation uses less memory and runs faster than the Full Simulation, but it does not provide the same levels of information and accuracy.


Full Simulation
: This is a full CFD simulation of fluid flow, taking into account momentum, pressure and velocity of the molten metal as well as viscous losses at the mold wall.



Q: What is CFD?

A: CFD stands for Computational Fluid Dynamics, which refers to a numerical solution of the Navier-Stokes equations that govern fluid flow.


Q: Does FLOWCast use the same models as SOLIDCast?

A: Yes. FLOWCast uses exactly the same models that SOLIDCast uses. You build your models in the same way, and mesh them the same way. FLOWCast uses the meshed SOLIDCast model to run its simulation.

 


Q: How do I run FLOWCast?

A: First of all, you build your model (with Fill Material) and mesh it just as you normally would in SOLIDCast. There are then two ways to start FLOWCast:

  1. If you only want to run a fill simulation with FLOWCast, without a subsequent SOLIDCast solidification simulation, you can select the Mesh icon on the SOLIDCast Project Tree, click on the Mesh menu item, and from the drop-down menu you can select Start FLOWCast. This will appear as follows:

This will bring up FLOWCast in an Interactive Mode , when you can use the FLOWCast menu to start a simulation, select between a Quick and Full simulation, change the view angle, set the percent increments for saving data, and make AVI movie files after the simulation is done.

  1. If you want to run a FLOWCast fill simulation and then automatically run a SOLIDCast solidification simulation afterward (using the results of the FLOWCast fill simulation as the starting point for the SOLIDCast run), then you would select the  
    Mesh
    menu entry and select Start Simulation as shown below:

 

You will then see the typical Simulation Start window as shown below, but with a difference: With FLOWCast installed you can select between the traditional SOLIDCast mold filling simulation, the FLOWCast Quick simulation, or the FLOWCast Full simulation, as shown below:

If you select one of the FLOWCast fill algorithms, FLOWCast will run in Auto-Run Mode. This means that FLOWCast will start automatically, run to completion, and then SOLIDCast will run a simulation of solidification, using the results of the FLOWCast fill simulation.


Q: If I run a FLOWCast simulation in Auto-Run Mode, how can I load it to see the fill simulation results?

A: If a FLOWCast simulation has been run on a mesh (in either Interactive Mode or

Auto-Run Mode) you will see a FLOWCast icon on the Project Tree that looks like this:

If you select Mesh and Start FLOWCast from the menu, FLOWCast will load the previous simulation run. You can then view this run or create AVI movies from it.


Q: If I have run a FLOWCast simulation in Interactive Mode, how can I run a SOLIDCast simulation of solidification using the FLOWCast results?

A: In this case, select Mesh and Start Simulation, and then select SOLIDCast as the Fill Algorithm. SOLIDCast will first check to see if the results of a FLOWCast simulation are available; if so, it will use these results as the starting point of a solidification simulation.



Q: Will FLOWCast work with permanent mold (gravity die-casting) simulations?

A: Yes! FLOWCast can be run in Auto-Run Mode for each cycle of a permanent mold simulation. If you use the option where initial cycles are run with a coarse mesh to warm up the mold and the final cycle is run with a refined mesh, you now have another option. You can choose to select one algorithm to use for the warm-up cycles and a different algorithm for the final cycle. This appears as follows:


Q: Can FLOWCast handle tilt-pour permanent mold simulation?


A: Yes! Just specify the tilt pour using the File Options menu selection in SOLIDCast while building the model. (Note: ONLY the Full FLOWCast algorithm may be used for a Tilt-Pour simulation. The Quick FLOWCast algorithm does NOT simulate tilt pour.)


Q: Can I run FLOWCast using mold temperatures that have already been calculated in a SOLIDCast simulation?

A: Yes! If you start FLOWCast in Interactive Mode (by selecting Mesh… Start FLOWCast from the SOLIDCast menus), and if a simulation has already been run on that mesh (which you can tell if there is a Simulation icon on the Project Tree) then the following selection box will appear:

This means that, if you start a FLOWCast simulation running, you can select to use either the initial temperature values of the materials or the temperature distribution as a result of the SOLIDCast simulation. So, for example, if you have completed a permanent mold simulation and want to run FLOWCast using the calculated temperature distribution in the mold, you can select  Use Temperature Data from the simulation and then start FLOWCast running with the mold temperature data.

Note: If a FLOWCast simulation has already been run on a mesh, that simulation will be loaded automatically when you start FLOWCast in Interactive Mode. You can select Restart in FLOWCast to start a new flow simulation running.


Q: How is FLOWCast data stored?

A: Before running a FLOWCast simulation, the user specifies a % increment for saving time-step data. This means that after the simulation is complete, you can view the filling at each of these percent increments but not in between. When AVI (video) files are created, they are created using these saved time steps. Saving at each 5% creates relatively large time steps; each 1% creates a relatively smooth video file. The size of the output data files depends partly on the number of time steps, and partly on the number of nodes. Note that you can set a separate increment for temperature data only. This allows you to save more temperature data, which is used most often, than velocity and pressure data. This helps to minimize file sizes.

FLOWCast creates large data sets. It is recommended that, after creating the output views or AVI files that you want from the simulation, you archive the project folder to a CD or other off-line storage medium, or delete the FLOWCast information from the project tree.

 

 Q: What information can FLOWCast display?

A: From a Full FLOWCast simulation, the system can display (and make AVI files of) temperature, velocity and pressure during the fill. A Quick FLOWCast simulation can show temperature and velocity. These types of displays are as shown below (in a partially-filled investment casting model):

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

You can also add flow pathlines and metal velocity vectors to the 3D plots and animations.


Q: What kind of computer should I have for running FLOWCast?

A: FLOWCast is very computationally intensive and creates a lot of data. Therefore, we recommend the fastest and largest computer that your budget will allow. At this time, this would mean a Pentium 4 machine running at 3.6 or more GHz, with 3 or 4 GB RAM, and at least a 100 GB hard drive.


Q: Can I run more than one FLOWCast simulation simultaneously?

A: No. Only one instance of FLOWCast may be running on a single computer at one time. Since FLOWCast uses such a large amount of memory, running multiple simulations, even on multi-processor machines is not practical.


Using FLOWCast s Interactive Mode

 

This section will take you on a quick tour of FLOWCast s most useful commands. In this Quick Start Guide, you should learn enough to be able to start and stop FLOWCast, change simulation and display modes, and generate video files of mold filling.

When you start FLOWCast by selecting Mesh… Start FLOWCast in the SOLIDCast menu, you are entering FLOWCast s Interactive Mode. When FLOWCast first appears, you should see a screen similar to this:

Note the Toolbar at the top of the screen, which looks like this:

The buttons on the Toolbar are used for controlling the simulation.


Q: How do I select between a Full Simulation and a Quick Simulation?

A: The hourglass button is used to toggle between Quick and Full. If this button is depressed, you are in Quick Mode. If it is popped out , you are in Full Mode. When FLOWCast is first started in Interactive Mode, it is in Full Mode.


Q: How do I start a FLOWCast simulation?

A: Just click the double arrow button to start the simulation running.


Q: How do I interrupt (stop) a FLOWCast simulation that is running?

A: Click the Stop Sign button. You may need to wait a few seconds for the simulation to actually stop, as FLOWCast needs a little time to organize its data for the stop.


Q: How do I restart a FLOWCast simulation that has been interrupted?

A: If you want to start from the same point, just click the double arrow again.

However, if you want to restart the simulation from the beginning, first click the Restart button as shown above. This will reset FLOWCast to the beginning. You can then make changes in parameters and press the Start button (double arrow) to start again.


Q: What will I see when FLOWCast starts running?

You will see the molten metal beginning to run into the mold cavity. This should look something like the following:

 



Q: How do I switch between viewing Temperature, Pressure and Velocity?

A: Clicking on Display (as shown below) allows you to select between Temperature, Pressure and Velocity displays (as well as some other display choices):

 

 

Let s see what the display looks like if we click on Velocity

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Here, the brighter colors represent areas where the velocity of the liquid metal is higher. We can see that the metal pouring down the sprue is obviously the highest velocity. The liquid in the runner between the sprue and gate, and the metal falling down the gate into the casting are all areas of higher velocity.

 

Selecting the Pressure display shows the following:

Here we can see relatively high pressure in the runner. Anywhere that the liquid is free-flowing and not under metallostatic pressure is a low-pressure area.

Note: You can change the display at any time, even while the simulation is running.


Q: How do I rotate the FLOWCast model to see it from different angles?

A: FLOWCast allows you to rotate the model in real time, as you can do in SOLIDCast. To rotate the model, click on the Rotate Model button as shown below, and then press and hold the left mouse button as you drag the cursor across the screen until the model is in the desired orientation.


 

This screen shows the model view after a rotation has taken place:

You can change the viewing angle at any time, even while the simulation is running.

There are a number of preset viewing angles that can be accessed from the View Control. Details are discussed in Unit 10 of this workbook.

 


Q: How do I set the percent time steps for saving flow simulation results?

A: This should be done BEFORE STARTING THE FLOW SIMULATION. First click on the tab labeled Filling. Then, enter a  percent in the field labeled Save every % filled. For example, if you want to save the filling data every 5%, then enter 5 in this field as shown below. This means that, after the fill simulation is complete, you can display the data at each of these increments. If you create an AVI file from the FLOWCast simulation, the individual frames of the AVI video will be at these increments.

Since the most interesting flow data usually occurs near the beginning of filling, you can set the save increment to, say, 1% initially. Then, when filling has evened out, stop the simulation, change the increment to a larger value, say 3% or 5%, and then continue the simulation. This will save on disk space.

You can also set a separate save increment for temperature data only, by adjusting the field labeled Save every % filled (anim only). Since temperature data is typically used most often, it is a common practice to save temperature data at 0.5% or 1% increments, and other data at 5% increments. This allows for very smooth animations to be made from temperature data, without creating huge data files for all the rest of the data.


Q: How do I create an AVI (video) file from the FLOWCast simulation?

A: This is normally done when the FLOWCast simulation is finished. You can, however, interrupt a FLOWCast simulation when it is partially complete and make an AVI file of the simulation up to that point.

To create an AVI file, first click on the tab labeled Status. The individual time step data will be shown in the window. (Note: If you select one of these time steps by clicking it with the mouse, the simulation at that point will be displayed.) Now, click the button at the bottom of the screen labeled Create AVI.


You have the choice of creating a realtime AVI, which runs at the actual pouring speed, or at a fixed number of frames per second.

 

The system will ask you to enter a name for the AVI file, and will also allow you to specify where the AVI file is to be placed. Once you have entered the file name, click Save.

The AVI file will be created at this point.

Note that the AVI file is created using the display type and viewing angle that are currently selected. You may typically want to create three AVI files, one showing temperature, one showing pressure and the other velocity. All you have to do to create these different files is to select the appropriate Display type next to the Tool Bar before creating the AVI file.

 


Temperature information can also be animated using the Anim Tab. Typically, you would save temperature data at a smaller increment, and so more data is available to make movies with. By saving, say, 200 time steps, a very smooth animation can be created. An example of what the Anim Tab looks like is shown above. The Create AVI function works in exactly the same way on the Anim Tab as it does on the Status Tab, but it only considers temperature information. If your display is set to any other data, when you click on Create AVI the system will switch over to temperature before creating the movie.


Q: How do I get back to SOLIDCast?

Just exit from FLOWCast, either by selecting File… Exit or closing the FLOWCast window with the X button in the upper right-hand corner. When FLOWCast closes, SOLIDCast is in a minimized state on the Windows Task Bar. Just click the SOLIDCast button on the Task Bar to restore the SOLIDCast window.

 

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