Archive for January, 2008

Choice of Pressure Boundary Condition in FloWorks

Wednesday, January 30th, 2008

At SolidWorks World 2008, Seth and I had the privilege of getting into a discussion with Bill Dziedzic, FloWorks Technical Specialist at SolidWorks Corp. and Arvind Krishnan, Product manager of FloWorks, about the correct usage of the pressure boundary condition in COSMOS FloWorks. It is to be kept in mind that FloWorks gives a user three choices when assigning a pressure boundary condition – static pressure, total pressure or environmental pressure.

The formal definitions of Static and Total Pressure are as follows:

Static pressure is the pressure indicated by a measuring device moving with the flow or by a device that introduces no velocity change to the flow. The usual method for measuring static pressure in a flow along a wall is to drill a small hole normal to the surface of the wall and connect the opening to a manometer or pressure gage. In the region of the flow away from the wall, static pressure can be measured by introducing a probe, which in effect creates a wall.

Total pressure is the pressure measured by bringing the flow to rest isentropically (without loss). A device for measuring total pressure is the Pitot tube, an open-ended tube facing directly into the flow, where the kinetic energy of the fluid is converted into potential energy.

Bernoulli’s equation states that Total Pressure = Static Pressure + Dynamic Pressure.

CHOOSING THE RIGHT BOUNDARY CONDITION

The decision to select Static or Total Pressure should be based off real testing procedures (whether the pressure at the outlet is measured by a manometer, or a pitot tube arrangement). In the event that one is unsure, it is always a good idea to pick the Environmental Pressure condition. This ensures that any potential reversals in fluid flow (like vortices across a pressure opening) are accounted for.

NOTE 1: If, during the calculation, a vortex crosses an opening with the Environment pressure condition specified, the pressure will be considered as the total pressure at the part of opening through which the flow enters the model, and as the static pressure at the part of the opening through which the flow leaves the model.

NOTE 2: It is important to remember that FloWorks uses Absolute Pressure values. Hence, 2psig should be specified as 16.69 psi in absolute terms (2 + 14.69psi atmospheric).

Vikram Vedantham

Simulation Product Manager 3DVision Technologies

The Best SolidWorks World Technical Training Session Ever

Friday, January 25th, 2008

What do you get when you take the best two SolidWorks World presenters and put them in the same room? Simply the best SolidWorks World Technical Training session ever!

Ed Eaton of the Dimonte Group is an industrial designer who has been doing his “Curvy Stuff” presentations at SolidWorks World for years. Even though I have hardly ever designed curvy stuff in SolidWorks I have never missed one of his presentations. Ed’s understanding of how SolidWorks “thinks” always fascinates me.

Phil Sluder of TriAxial Design is a mechanical engineer who has given a presentation at SolidWorks World every year. I have to admit I have missed a few of them but the ones I have attended I have left with pages of notes -the guy knows how get the most out of the SolidWorks software.

The last day of SolidWorks World was capped off by Ed and Phil teaming up putting together the presentation titled: “Sluder and Eaton Take on your SolidWorks Problems”. I liked the concept, they each took several real world modeling questions and answered how they would solve them. Since they both have drastically different backgrounds I was expecting some rather heated debates and two unique ways to solve the problems.

The debates never happened and their solutions were rather similar -however the educational and entertainment value was just what I hoped for!

They started out with a part they found in a blog posting by Elise Moss. She found a part that has many [patterned] holes in it. The part did not look like it was very complex but it had terrible rebuild times. They challenged each other to improve rebuild performance. First both noticed that turning off the option: “verification on rebuild” significantly improved performance. (over 90%!) They weren’t done, knowing that complex features later in the feature manager run faster than if they are earlier in the feature manager they found significant improvement just by reordering the features in the part. Moral of the story, spend time with the “feature statistics” tool in SolidWorks, tweak your features and their order to learn how SolidWorks builds models. It CAN make a difference. (Just don’t spend more time tweaking a model to improve performance than you would ever save!)

Other quick hits:

  • Since it is true complex features work better at the end of the feature tree, if you have several complex features sometimes you can see performance improvements if you break the part into multiple sub parts.
  • Back a few versions ago SolidWorks no longer automatically displayed the “update folders” in assemblies. They were so handy when inspecting your in-context relationships in the parts of your assemblies. I don’t know why they did this, but did you know they are still there? Just right mouse click on the assembly feature, the option to display them is there!
  • Want SolidWorks to handle your slip and press fit dowel holes and call them out by your standards on drawings? Try creating your own custom standard in the hole wizard!

There was so much more. There was a filming crew there recording the entire session and the PowerPoint presentation was promised to be available as well. Keep your eye out for it, you won’t be sorry!

Jeff Sweeney

CSWE Engineering Data Specialist 3DVision Technologies

More control in SP4

Friday, January 25th, 2008

DriveWorks 6, service pack 4 has a great new control for your dialog boxes. It allows your users to enter in linear dimensional values in any units they choose and DriveWorks will do the conversion for you. Users can even enter in mathematical formulas. It acts like the dimensional input box that you use in SolidWorks!

This is certainly one of those “I cannot believe it took them this long to add it!” -but it is nice that they did.

Jeff Sweeney

CSWE Engineering Data Specialist 3DVision Technologies

New design automation web sites

Monday, January 14th, 2008

There is now a web site completely devoted to supporting the growing DriveWorksXpress community. If you get a chance go check it out. It has forums, tutorials and videos, FAQs and examples -everything you need to keep your design automation heart happy!

Speaking of design automation, have you seen SolidWorks’ new design automation micro-site?

DriveWorksXpress has been available as a free download for several years now. Isn’t it amazing how much more interest there is in design automation now that DriveWorksXpress is included in the core SolidWorks product?

Jeff Sweeney

CSWE Engineering Data Specialist 3DVision Technologies

On the fly email notifications

Thursday, January 3rd, 2008

A common PDMWorks Enterprise enhancement request is to give the users the ability to pick and choose who gets notified when a document goes through a workflow transition.

While personally that request seems like it would make a loophole users could use to get around the system i.e. not notifying your manager or quality control if a document is approved. -I’ll grant there may be cases where it would be useful.

So I thought I’d give you a little application that could be used to get you started in creating your own. There are fancier ways this could be done but this provides a very flexible solution and the price is right eh?

The program would be kicked off as an “action” as a document goes through a transition. [As an example see screen shot.]

Transaction

Note the full file name is sent as a command line argument using the “File Path” tag. This is how the file name gets sent to the program. Additionally, ensure the compiled .exe program is in a location where everyone has access to it.

Once started by the PDMWorks Enterprise transition, this routine simply creates a pre-populated Outlook message -populated with anything you choose. Typically the body of the message wouldn’t need to contain much -mostly just containing a link to the file that triggered the routine and some minimal instructions. The user would then, in this Outlook message, choose who to send the email to. He could also modify the body of the email if he chose. Then when the email looks as he likes he simply clicks “send”.

Here is the .NET code. Feel free to modify it to fit your needs, just keep the first comment line in! :)

Imports Microsoft.Office.Interop
Imports Microsoft.VisualBasic
Module modMain
Public Sub Main()
'by Jeff Sweeney, may he live long and prosper
Dim strFileName As String = Interaction.Command()
Dim objOutlook As Outlook.Application
Dim objNameSpace As Outlook.NameSpace
Dim objMailFolder As Outlook.MAPIFolder
Dim objMailItem As Outlook.MailItem
objOutlook = CreateObject("Outlook.application")
objNameSpace = objOutlook.GetNamespace("MAPI")
objMailFolder = objNameSpace.GetDefaultFolder(4)
objMailItem = objMailFolder.Items.Add
objMailItem.Subject = "A file needs your approval"
objMailItem.HTMLBody = strFileName & " has gone through a transition and requires you to do something"
objMailItem.Display()'gives the user a chance to modify
objMailItem = Nothing
objMailFolder = Nothing
objNameSpace = Nothing
objOutlook = Nothing
End Sub
End Module

Tip: Don’t forget you will need to add Outlook as a reference in your .NET project. Otherwise simply compile as a “Console Application” and you are set!

This is just the tip of the iceberg. You could change the routine to accept more than one parameter. An additional parameter could be the transition name, so you could get different emails depending on the transition that called it. You could have the routine examine the extension of the file and do different things depending on the file’s extension.

I’d love to learn how you end up using it!

Jeff Sweeney

CSWE Engineering Data Specialist 3DVision Technologies

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