{"id":24141,"date":"2015-01-08T07:00:37","date_gmt":"2015-01-08T12:00:37","guid":{"rendered":"https:\/\/blogs.solidworks.com\/solidworksblog\/?p=24141"},"modified":"2015-01-05T14:54:02","modified_gmt":"2015-01-05T19:54:02","slug":"goals-in-solidworks-flow-simulation","status":"publish","type":"post","link":"https:\/\/blogs.solidworks.com\/solidworksblog\/2015\/01\/goals-in-solidworks-flow-simulation.html","title":{"rendered":"Goals in SOLIDWORKS Flow Simulation"},"content":{"rendered":"

One of the key technologies in SOLIDWORKS Flow Simulation is a\u00a0concept in the software called Goals. \u00a0My hope in the post is to attempt to clear up any questions that you may have about Goals by breaking it down into 3 sections: first, what is the purpose<\/strong> of using Goals; second, what are the different types of Goals<\/strong>; and lastly, how to define<\/strong> them.<\/p>\n

Purpose of Goals<\/strong><\/p>\n

The Goals in SOLIDWORKS Flow Simulation serve 3 purposes:<\/p>\n

    \n
  1. Defines Design Goals and\/or other important criteria<\/li>\n
  2. Used for Convergence Control<\/li>\n
  3. Finish the calculation<\/li>\n<\/ol>\n

    The main purpose of Goals is to define for the project\u00a0what are the key design objectives for your simulation. Some examples might include maximum velocity in the Y-direction globally or a component’s average temperature. \u00a0After solving the problem and\u00a0reviewing the results, you can very quickly ask the software to\u00a0view\u00a0a table of your goals or automatically create one in an Excel spreadsheet. \u00a0This is great for a visual summary of your project. \u00a0Putting the goal chart to work in the Compare Tool also provides an insightful\u00a0comparison of results from other projects, where you have either varied the model geometry or a flow parameter. \u00a0Not the least to mention that while solving the problem, you can view updated values for the Goals in the solution monitor window.<\/p>\n

    Because the equations governing fluid flow are highly nonlinear, the problem is solved iteratively where the parameters are updated in every computational cell\u00a0in each solution step. \u00a0You can track these iterations by monitoring the Goals in both a table and plot. \u00a0Initially the Goals will change a good bit, but eventually they will\u00a0not change as much and will begin to level out to some\u00a0value. \u00a0The software itself has some built-in functionality for\u00a0convergence\u00a0of the solution, but with Goals it gives the user confidence that their key design criteria are\u00a0accurate.<\/p>\n

    The solver could run indefinitely, but at some point the solution is changing very little with successive iterations, so you have to end the calculation. \u00a0And Goals are a great way to indicate that the flow parameters have converged to a certain solution and it is reasonable to finish the solution. \u00a0Because of the conservative structure of the software, most times this is well before the internal convergence criteria would have stopped the solver, so you save valuable time by defining Goals.<\/p>\n

    Note that in the above items 2 & 3, I made the assumption that the problem being solved is a steady calculation and not changing with time as transient solution would. \u00a0Goals are still important in a transient solution as you can still monitor them during the calculation. \u00a0But know that the parameters\u00a0may never converge because they are constantly changing in time. \u00a0And instead of Goals being used to finish the calculation, you typically run the calculation up to a specific physical time for which you then stop.<\/p>\n

    Types of Goals<\/strong><\/p>\n

    There are 5 goal types:<\/p>\n

      \n
    1. Global Goals<\/li>\n
    2. Point Goals<\/li>\n
    3. Surface Goals<\/li>\n
    4. Volume Goals<\/li>\n
    5. Equation Goals<\/li>\n<\/ol>\n
      \"\"<\/a>
      SOLIDWORKS Flow Simulation Goal Types<\/figcaption><\/figure>\n

      A Global goal\u00a0is\u00a0a physical parameter calculated in the entire Computational Domain, which is the box that encompasses the entire fluid and\/or solid volumes where the solution is solved. \u00a0One use of a global goal is to find out what is the maximum temperature for all the solid components in the model.<\/p>\n

      A Point goal is a value at a specific point, and can be specified either by a reference or 3 coordinate values. \u00a0I personally don’t use this goal very much, but it would be useful to someone who wants to compare the computed results to physical test data at a given point. \u00a0(Check out the Probe in the Results tools for grabbing computed data on plots at a point.)<\/p>\n

      Surface goal is a parameter on selected surface(s). \u00a0Many times I’ll pre-select one of the inlet or outlet boundary conditions to use as a surface for this goal type. \u00a0If you choose a parameter such as Total Pressure, you can request the min, average, max or bulk average value\u00a0on that\u00a0surface; or if you choose mass flow rate, for example, you will get the integral value for the entire surface. \u00a0Surface goals are very useful for getting pressure drops, as I will explain when talking about Equation goals later.<\/p>\n

      A Volume goal is a parameter within specified volume(s); it can be applied to parts, components within a subassembly and even bodies within a multi-body part, essentially whatever defines a volume. \u00a0Like surface goals, you can select more than one surface or volume (depending on the goal type). \u00a0I often use a Volume goal\u00a0as a “Component” goal to find the temperature of a specific component.<\/p>\n

      Last, but not least importantly, is an Equation goal which can be defined using anyone of the previous goal types in a mathematical equation. \u00a0A very simple example is to subtract a surface pressure the inlet from the surface pressure from the outlet\u00a0to get the pressure difference, or more specifically a pressure drop for the system. \u00a0You may also use combine them together to use one equation goal in another. \u00a0An equation goal is very powerful, as you might gather, because it can be used\u00a0to calculate such design objectives as Cv (or valve flow coefficient), heat exchange efficiency, pump efficiency, and drag coefficient.<\/p>\n

      Defining Goals<\/strong><\/p>\n

      The most direct way to define a goal is to right-click on the Goals icon (a black-and-yellow checkered flag)\u00a0in the SOLIDWORKS Flow Simulation tree to choose your goal type. \u00a0You can also do it through a menu following Flow Simulation > Insert and the goal types are at the top of that listing.<\/p>\n

      \"Surface<\/a>
      Surface goal definition user interface<\/figcaption><\/figure>\n

      A\u00a0screenshot\u00a0of the Surface Goals definition is given above. \u00a0First, one or more surfaces need to be provided in the selection\u00a0box. \u00a0Then you can select any of the boxes next to the named parameters. \u00a0You see the boxes in columns listed for minimum (Min), Average (Av), maximum (Max) and bulk average (Bulk Av), and the last column is by default selected to include the goal to be used in convergence control (Use for Conv). \u00a0You may also selected more than one box for min, av, max or bulk av from the list and to define multiple\u00a0separate goals in the tree.<\/p>\n

      In this example, since I wanted to use the same face that I had used to define the inlet, you\u00a0can do the following (which if you click on the animated GIF image below will show you the steps):<\/p>\n

      After choosing to define the Surface goal and the dialog interface\u00a0comes up, you may select the Flow Simulation tab at the top of the tree to split and reveal the input items. \u00a0By selecting the boundary condition that was named “Inlet Volume Flow 1” be default, it will add that same face into the surface goal selection box. Then I define my goal to be an average static pressure goal on that face.<\/p>\n

      \"Click<\/a>
      Animated GIF: Surface plot definition of Static Pressure using the inlet face<\/figcaption><\/figure>\n

      I only provided a general overview on Goals here, as\u00a0there is much more that I could have delved into each sub-section, but I feel that I achieved the purpose that I set out for this post. Hopefully this post will help you on your way to understanding Goals in SOLIDWORKS Flow Simulation better. \u00a0If you want to learn more or have questions, please write me\u00a0comments in the section\u00a0below.<\/p>\n","protected":false},"excerpt":{"rendered":"

      One of the key technologies in SOLIDWORKS Flow Simulation is a\u00a0concept in the software called Goals. \u00a0My hope in the post is to attempt to clear up any questions that you may have about Goals by breaking it down into<\/p>\n... Continued<\/a>","protected":false},"author":172,"featured_media":24147,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[88],"tags":[465,437,2081,2078,461],"class_list":["post-24141","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-solidworks-flow-simulation","tag-cfd","tag-flow","tag-solidworks-flow-simulation","tag-solidworks-simulation","tag-tips"],"acf":[],"_links":{"self":[{"href":"https:\/\/blogs.solidworks.com\/solidworksblog\/wp-json\/wp\/v2\/posts\/24141","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.solidworks.com\/solidworksblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.solidworks.com\/solidworksblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.solidworks.com\/solidworksblog\/wp-json\/wp\/v2\/users\/172"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.solidworks.com\/solidworksblog\/wp-json\/wp\/v2\/comments?post=24141"}],"version-history":[{"count":0,"href":"https:\/\/blogs.solidworks.com\/solidworksblog\/wp-json\/wp\/v2\/posts\/24141\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.solidworks.com\/solidworksblog\/wp-json\/wp\/v2\/media\/24147"}],"wp:attachment":[{"href":"https:\/\/blogs.solidworks.com\/solidworksblog\/wp-json\/wp\/v2\/media?parent=24141"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.solidworks.com\/solidworksblog\/wp-json\/wp\/v2\/categories?post=24141"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.solidworks.com\/solidworksblog\/wp-json\/wp\/v2\/tags?post=24141"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}