Simulation of chill ripples formation
during glass pressing

Figure 1: Setting up the pressing chill ripples case in the GUI

Figure 2: Zoomed temperature results to see the chill ripples

Figure 3: Animation glass pressing and chill ripples formation

The simulation of chill ripples formation during a glass pressing process can perfectly be performed with our CFD software NOGRID points. If hot glass comes into contact with cold forming tools, three different kinds of typical hot forming defects usually limit the process window in glass forming processes. The first defect is sticking of the glass at the forming tools (chemical reactions between glass and forming material occurs), if the temperature is above a certain value. The second type of defects are hot forming cracks in the glass and the third forming defect is the appearance of chill ripples, which occur if the temperature of the forming tool is too low. Chill ripples are also known as press ripples or flow ripples. Sometimes these ripples can be observed on hollow ware products, such as pressed wine glasses, in the form of concentric waves on the surface of the foot.

In the 2D example shown here, both the metal forms (mold and plunger) and the glass are computed as solids. Since the two metallic solids and the liquid glass are computed together in one model, this is also referred to as a so-called multi-phase flow. If the hot glass comes into contact with the cold tools, a contact temperature and a flow of heat are set up immediately. The cold metal molds heat up and the hot glass cools down.

NOGRID points computes the real glass flow and temperature distribution during the complete forming step and is also able to predict the appearance of chill ripples. Comparisons with various experimental data have shown the high precision of the simulation of this intricate flow process. The short computation time allows our customers incorporating the simulation into the design process to find an optimal design, thus saving time and effort in the design phase and increasing product quality.

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

  • computation is in full 3D solving complete Navier-Stokes-Equations
  • easy and intuitive setup
  • free definable material properties by equations or curves also for non-Newtonian fluids
  • evaluation of chemical reactions and corresponding heat source terms
  • open or closed domains including inflow and outflow areas (non-batch mode)
  • moving of parts 

Nogrid's strengths

Particular strengths of NOGRID's fluid flow CFD software are the rapid preprocessing (no fluid grid needs to be generated, only the boundary mesh, inner finite points are generated automatically depending on User setting initially and during computation), and the outstandingly short computation time even for complicated cavities.
As you can see in the image below, the boundary of the geometry still requires a mesh to allow the interior finite points to detect the boundary. The boundary must therefore be meshed and the finite points inside are automatically generated during the simulation controlled by User specifications.
Easy Modelling

Easy and fast modelling: Build geometry, mesh boundary, setup the case and start computation

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 for flow modeling 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.

For more details please refer to Training Courses →


Technical Support


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

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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.

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