The post CFD simulation of Porous Material appeared first on Idra Simulation.

]]>Different industrial applications involve the modeling of flow through porous material, like water filtration, catalyst beds, packing, etc.

Darcy-Forchheimer law can be used on the Porous media to characterize the pressure drop:

Where *S* is a source term added to the Navier-Stokes equations. This term is composed of a viscous loss term and an inertial loss term, creating a pressure drop that is proportional to the velocity and velocity squared, respectively.

The constants *D* and *F* have physical meaning and could be calculated based on permeability and Ergun’s coefficient, but in this work they have been determined by curve fitting of the pressure/velocity curves of the porous material.

This image shows streamlines passing trough the filling material and drift eliminator of a cooling tower:

The simulation has been performed at Idra Simulation on a 3.7 millions elements mesh.

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]]>The post From Design to Prototype using Topology Optimization appeared first on Idra Simulation.

]]>*Topology optimization* determines the distribution of material most suitable to a given objective. It is primarily used to produce a fundamental basis for the engineers at the conceptual design stage, or to generate ideas for new alternatives.

In order to express the distribution of materials in topology optimization, **density variables** of the finite elements created for analysis are used. The element density of 1 represents a part that requires the element, while 0 represents a part that does not require the element. Unlike parametric optimization, the only design variable is the element’s density. As such, the user does not specify separate design variables but composes an optimization problem using only the combinations of objective functions and constraints.

Like any optimization problem, *Topology optimization** *includes the following fundamental elements:

**Objective**: In this problem, the objective is to minimized the static compliance (a function of element density expressed in the form of global deformation energy):

Where:

f : Load vector

u : Global & element displacement vectors

K: Global & element stiffness matrices

**Design variables:** Volume fraction (the n_nodes density values which determine whether material is present (1) or absent (0))

**Geometric constraints**: the initial unoptimized geometry:

**Design evaluator:** the linear elasticity solver of MidasNFX, that calculates deformation energy based on specified loads and boundary conditions.

Since we are looking for general guidelines of an optimal design (in practice, we should say “better design”), the next step consists of modifying the original CAD geometry to remove material when it’s not needed:

Topology optimization often leads to complicated organic-like products that cannot be manufactured using traditional processes (which is not necessarily the case here). Additive manufacturing, like **3D printing**, is sometimes more adapted for this kind of design. Here, a printed version of the optimized part is produced.

This video summarizes the whole process:

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]]>The post Nonisothermal Flow Simulation with Midas NFX appeared first on Idra Simulation.

]]>A simple model, with a lot of added value! For this project, Midas NFX has been used to control the thickness of the *thermocline* (the layer of fluid where the temperature changes rapidly).

The container is initially filled with warm water, and the inlet of cold water progressively replace it. The shape of the diffusers and the flow rate are adjusted to keep the thickness of the thermocline under a critical value.

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]]>The post Midas NFX 2017 Released appeared first on Idra Simulation.

]]>**midas NFX 2017** is now available to all our clients. If you still don’t use NFX and you want to try it, contact us to have a free evaluation version.

The **2017** release includes several major improvements for modeling, contact creation, optimization and post processing. For more details, consult the release notes.

There’s more! See the release notes.

The post Midas NFX 2017 Released appeared first on Idra Simulation.

]]>The post Simulating prehistoric life appeared first on Idra Simulation.

]]>This short film presents an original application of HPC, namely *Agent-based social simulation* applied to prehistoric life:

The video is produced by the BSC Scientific Visualization Team. This center is also developing *Alya* (see this previous post about Alya), a multi-physics code designed to run efficiently in supercomputers.

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]]>The post Frequency sweep analysis using code_aster appeared first on Idra Simulation.

]]>code_aster offers numerous dynamic analysis options: full transient (see “Dynamic stability of 3d-printed device“), modal, spectral and harmonic. This post presents an example of the latest applied to a 8 stories building.

The harmonic analysis can be performed directly in the physical space, or by the modal superposition method – which could be useful for large problems (superposition of modes of the full structure or a series of sub-structures).

The macro commande DYNA_VIBRA gathers many of the dynamic options under a single command, e.g.:

Haro = DYNA_VIBRA( TYPE_CALCUL='HARM', BASE_CALCUL='PHYS', MATR_MASS=M3, MATR_RIGI=K3, MATR_AMOR=C3, LIST_FREQ=listfreq, EXCIT=_F(VECT_ASSE=F3, COEF_MULT=1.0), );

The new DEFI_LIST_FREQ command creates a list a frequencies to sweep with an automatique refinement around the natural modes of the structure.

**For training or consulting using code_aster, contact us.**

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]]>The post Fusion 360: professional CAE software for 20€/month appeared first on Idra Simulation.

]]>As mentioned in this blog some weeks ago, CAD is moving on the cloud. A “new” player in this market is Autodesk’s **Fusion 360**. It would be difficult to describe all the features of this revolutionary tool here, so visit this link. If you are not convinced yet, see:

Not enough? They have a big active user community, a good technical support and you can write scripts with an API:

You may or may not like Autodesk’s decision to stop selling perpetual licenses, but you have to admit that 20 €/month for Fusion 360 is a good price. Yes, I said 20€.

A last important detail for FEA user: you can do “**direct modeling**” on imported parts. But I let this for another post…

For all those reasons, Idra Simulation decided to adopt it. This option is more flexible than the expensive licenses of *SolidWorks*, *Creo* and cie (their maintenance fees alone are more expensive than Fusion 360); and the few active open-source CAD projects are not yet ready for the industry.

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]]>The post Proof of Concept test for electric water heater appeared first on Idra Simulation.

]]>This animation shows a proof of concept geometry for an electrical water heater:

Two graphite electrodes are immersed in a water tank. Three physics are involved. First, the **static current conduction** equation is resolved. Then, **Joule heating energy** is calculated in the entire geometry and used as a body force for the **heat equation**. Finally, temperature calculated is introduced in the **Navier-Stokes equations**.

**For training or consulting using Elmer, contact us.**

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]]>The post Numerical study of shrink ring and die interference appeared first on Idra Simulation.

]]>Prestressing technique is used to decrease the tensile stresses that develop in a metal forming die (powder compaction, extrusion, stamping, etc.). In order to increase die life and to protect the shrink ring, the interference value between the two parts must be optimized.

The iterative variation of the design parameters (interference, diameters, material properties) using numerical simulation leads to a reduction of time and resources invested. This process can be automated with Code_Aster in order to obtain an optimal design.

The tendency is usually the following: a **higher** interference leads to **lower** tensile stresses in the die during compaction, but to a **higher** stress in the shrink ring. Consequently, the optimized interference should be find to take advantage of the pre-stress tensional state of the die, without damaging the shrink ring. The failure of the shrink ring would reduce the fatigue resistance of the die.

The maximum principal stress for interference values of 0.05, 0.1 and 0.15 mm are shown on this image (section in the middle of the compacted part):

Download the “white poster”: Die_prestressed.pdf

**For training or consulting using code_aster, contact us.**

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]]>The post Code_aster adaptive meshing appeared first on Idra Simulation.

]]>code_aster integrates an automatic adaptive mesh algorithm based on error estimation. The idea is simple: where the error is important, the mesh is refined; where the error is small, the mesh is coarsened. The mesh is adjusted until the convergence criteria is reached:

**For training or consulting using code_aster, contact us.**

The post Code_aster adaptive meshing appeared first on Idra Simulation.

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