Parent Category: Industries


Fuel tanks made by plastics allow for weight reduction and high accuracy in comparison to steel tanks and they are free in design to fit into given space. The blow molding allows to produce tanks with complex geometry. The challenges are the stability under pressure, the integration of internal components and the chemical resistance against the fuel. A key question in the design is the wall thickness of the tank. It is a result of the initial thickness of the plastic parison and the flow properties of the melted plastic.


Simulation (CFD) Blow Molding Tank

Figure 1: Extrusion blow molding process in full 3-D (no shell elements) using a flat parison with variable thickness

Three main types of blow molding are widely used (extrusion blow molding, injection blow molding, and injection stretch blow molding) and in this article we present an extrusion blow molding process in full 3-D by which two (initially flat) plastic parts are formed and joined together later. Forming means that the flat parison of variable thickness is blown into a cavity and held there until it is sufficiently cool. The meshless CFD software NOGRID points can help to understand all phases of the blow molding process, beginning with the clamping (or pressing) of the sheet in the tool, the pressure loading, the first touch of the sheet at the wall and the final stretching to all corners of the tank geometry.


  1. Construct or import a geometrical model by using our pre-processor CAD tool COMPASS

    Blow Molding Tank CADFigure 2: CAD model created in NOGRID's COMPASS

  2. Set up all parameters like blow pressure or material/fluid properties

    Simulation results blow molding tankFigure 3: Simulation results shown in NOGRID's GUI (results format is Ensight, so Ensight or Paraview can be used as post-processor as well)

  3. Perform a simulation
    Blow molding tank simulation - Thickness distribution
  4. Figure 4: Initial extruded flat parison with variable thickness distribution in full 3-D (no shell elements)


NOGRID unites abilities to handle free surface flow and moving parts in the domain and allows the simulation of any conceivable mold geometry and operation modes such as

  • blow sheets with individual thickness distribution
  • computation is in full 3-D solving complete Navier-Stokes-Equations
  • moving of the middle part (for clamping or pressing)
  • free definable material properties by equations or curves,
  • large tank geometries with small gaps or cutouts and
  • open or closed molds including moving of the middle tool (plunger).
NOGRID's particular strengths are the rapid preprocessing (no grid needs to be generated) and the outstandingly short computation time even for complicated cavities.

What is CFD from NOGRID?

CFD solves the fundamental equations that define the fluid flow process. With CFD software from NOGRID every engineer makes better decisions by predicting, analyzing and controlling fluid flow, heat and mass transfer or chemical reaction. By using NOGRID software you receive information on essential flow characteristics as for example flow distribution. Using it additional to testing and experimentation NOGRID software helps to improve the evaluation of your design – resulting in better construction and operation parameters, increasing planning security and money savings due to faster time to the marketplace for your product or process.


With NOGRID, you choose professional CFD software and services – our aim is helping you to be successful. When you decide to work with NOGRID you choose close cooperation with a dynamic, flat hierarchies-organization. Short information channels result in quick and accurate professional support and service. Our team consists of highly qualified employees, who are experts in fields such as numerical simulation or computational fluid dynamics. Based on our know-how, we are pleased to offer the following services, responding to your individual requirements:


In our two-days training courses you will learn, how to use NOGRID CFD software efficiently. Our technical support team will teach you how to handle and solve different cases.


We offer full professional support from the minute you start using our software, by telephone or by email. Contact us, when ever needed.


Lack of time or resources and other constraints often make outsourcing an attractive solution. We help you with your flow modeling needs. Based on our engineering expertise in this field we offer individual numerical simulation services matching the unique needs of your organization.