## SC/Tetra

SC/Tetra è il software CFD generarl purpose per la simulazione termofluidodinamica basata su mesh di tipo ibrido (hybrid mesh or h-elements). Il vantaggio di questo tipo di mesh (h-elements) è dato dalla accuratezza con la quale è possibile rappresentare la superficie del modello, senza limiti di complessità geometrica. SC/Tetra è caratterizzato da un sofisticato generatore di mesh, dall'elevata velocità di calcolo, da un uso parsimonioso della memoria RAM e dall'interfaccia utente intuitiva. Tutto al fine di ottenere risultati affidabili con il mimimo sforzo.

## Introduzione

SC/Tetra è il software CFD generarl purpose per la simulazione termofluidodinamica basata su mesh di tipo ibrido (hybrid mesh or h-elements). Il vantaggio di questo tipo di mesh (h-elements) è dato dalla accuratezza con la quale è possibile rappresentare la superficie del modello, senza limiti di complessità geometrica. SC/Tetra è caratterizzato da un sofisticato generatore di mesh, dall'elevata velocità di calcolo, da un uso parsimonioso della memoria RAM e dall'interfaccia utente intuitiva. Tutto al fine di ottenere risultati affidabili con il mimimo sforzo.

## High-speed automated mesh generation

High quality mesh is automatically generated at a high speed by creating the octree and using the Advancing Front method. Prism layer elements affecting the calculation accuracy can also be created automatically and the layer thickness can be set to link with the width of a flow channel. The software enables faster mesh generation in parallel computing and supports large scale mesh.

## Mesh adaptation analysis

With this function in a steady-state analysis, mesh will be automatically refined at an area where the flow or pressure changes greatly. After Solver completes the calculation, Preprocessor is automatically launched and remeshing is executed based on the calculation result. You can generate a coarse mesh first and refine the mesh automatically. The function is useful for an analysis of flows in a tube of a complicated shape.

## Modifying CAD data

When CAD data to be used for simulation has a problem, the data can be modified in SC/Tetra. Boundary conditions can be set based on the part names and color information set in the CAD data. When some regions are missing in the model, shapes such as cuboids and cylinders can be added.

## Free surface

The function is used to calculate the shape of an interface between a gas and a liquid. VOF method (Interface Capturing Method) enables high-speed calculation with high-accuracy. The function can be used with other functions such as moving boundary, overset mesh, and particle tracking. The function is useful to analyze the effect of waves to a ship and the effect of shaking to a gasoline tank.

## Dynamical function, Moving elements

Passive translation and rotation of a rigid object receiving a fluid force can be analyzed. The object can be set to translate and rotate with up to 6 degrees of freedom. The function enables an analysis with a restraint condition (a spring for example) and an analysis of contacting objects. The function can make the simulation result of a check valve more realistic.

## Cavitation

The function enables simulation of a vaporization phenomenon called cavitation, which is caused at an area where pressure of a liquid becomes lower than in the surrounding area. The occurrence of cavitation can be predicted by applying the cavitation model based on the pressure values. The software also supports problems caused by cavitation such as erosion.

## Moving elements,discontinuous mesh

Flow with motion of objects can be calculated. Motion of objects is, for example, rotation of fans and turbines, and translation such as automobiles or trains passing each other. By combining rotation and translation, various and more complicated phenomena of moving objects can be simulated.

## Overset mesh

By overlapping mesh for a stationary region with mesh for a moving region, a motion which was not able to be simulated using the existing functions such as deformation or rotation can be simulated. In addition, contact of objects and overlap of multiple moving regions are supported. This function is useful to analyze opening and closing of a valve of an engine port, and a gear pump that works with its gears.

## SmartBlades

This function is useful to analyze the shape of a fan automatically throughout the following process: creating the shape of a fan (CAD data), calculating the flow, and post-processing. The shape of a fan can be created easily by specifying parameters including the number of blades, fan diameter, rake angle, and skew angle. An optional license is mandatory.

## Functions for turbomachinery

One-pitch shape can be extracted from a periodic model such as an impeller or a vane of turbomachinery. Then, the analysis result of the one-pitch model can be checked in the meridian plane. Two regions whose pitches are different can also be analyzed. The calculation load will be reduced by using this function.

## FSI option (Abaqus)

This option is used for fluid-structure interactive coupled simulation (FSI) by SC/Tetra and Abaqus (structural analysis software). Deformation of an object caused by a fluid force and the change of fluid caused by deformation of the object can be analyzed. An optional license is mandatory.

## Structural analysis option

By using the analysis results including values of pressure and temperature, deformation and thermal stress of an object can be calculated. The target of the structural analysis software bundled with SC/Tetra is within the range of linear static analyses. An optional license is mandatory.

## Compressible fluid

The software can analyze phenomena such as supersonic flow and significant expansion /contraction of volume. For a compressible fluid, both the pressure-based and the density-based solvers can be used. The density-based solver keeps the calculation stable even with high Mach number. You can select either solver depending on the analysis target and phenomenon.

## Analysis of sound of fluid

Sound caused by pressure oscillation of a fluid, such as wind noise, and sound caused by resonance can be predicted. The calculation can be performed accurately by using LES and the weak compressible flow model. The frequency of sound of fluid can also be analyzed using the Fast Fourier Transform (FFT) method from the CFD analysis result.

## Boiling model

Boiling heat transfer on walls can be analyzed. Boiling heat transfer on walls change depending on temperature or the state of air bubbles and is not constant. Simulating small air bubbles requires large calculation load. The boiling model, which simulates air bubbles caused by boiling, can be used to analyze complicated phenomena of heat transfer with small calculation load.

## Solidification, melting

The phase change between fluid and solid, for example, water to ice and ice to water, can be considered. The following phenomena related to solidification/melting can be considered: change of flow affected by a solidified region, change of melting speed depending on the flow status, and latent heat at melting. In this way, simulations closer to real phenomena can be done by using solidification/melting function.

## Dispersed multi-phase flow

You can analyze multi-phase flows containing many air bubbles, liquid droplets, or particles (dispersed phase) such as the bubble jet effect and an aeration tank. The dispersed multi-phase flow model regards the dispersed phase as a fluid (continuous phase). You can output distributions of volume fraction and velocity of each phase by using the model.

## Particle tracking

The behavior of particles depending on their characteristics (diameter, density, and sedimentation speed) and action and reaction between particles and a fluid can be considered. Various phenomena and actions of particles such as the following can be analyzed and considered: mass particles (sedimentation due to gravity, inertial force) and charged particles (movement due to electrostatic force, liquefaction at adhering on a wall surface, evaporation and latent heat, the behavior as bubbles in a liquid).

## Humidity dew condensation

The amount of dew condensation on an object surface can be calculated from the surface temperature and water vapor in the air. You can output the amount of dew condensation per unit time in a steady-state analysis and the accumulated dew condensation in a transient analysis. Evaporation from a surface where dew condensation occurs can be calculated simultaneously, and this is useful for an analysis of a windshield defroster.

## Liquid film model

The liquid film model is an extended function of particle tracking function. By using the model, you can simulate the phenomenon that a liquid particles change to a liquid film (water on a wall) when the liquid particle reach on the wall. A liquid film on a wall flows down depending on an angle of the wall and collects in a certain position. The analysis results are output as the thickness of a liquid film.

## Pressure loss model

A pressure loss model of a fluid passing through porous media such as punching metal, a slit, or a sponge can be used to ease the geometry representation. The pressure loss can be arbitrarily set by the power law of velocity. The opening ratio and the direction that pressure loss affects can also be considered.

## Coupled analysis with GT-SUITE

Coupled analysis between SC/Tetra and GT-SUITE is available. The entire flow in an intake and exhaust system is calculated with GT-SUITE and small flows of each part are interpolated with SC/Tetra. This will improve calculation accuracy of the whole system. An optional license is mandatory.

## Thermoregulation-model (JOS)

Combination use of the thermoregulation-model (JOS) and a fluid analysis provides the surface temperature of the human body. You can consider age, clothes, and physiological phenomena of the human body such as heat transport by blood flow in addition to surrounding environment of the human body such as temperature and velocity. SC/Tetra adopts JOS and JOS-2 developed by Waseda University Tanabe Laboratory et al. as thermoregulation models

## LES

LES is one of turbulent flow models. It models small eddies and directly calculates others. Although calculation load is large, LES enables simulations closer to real phenomena. LES is often used in noise analyses, significantly affected by time variation, to simulate the behavior of small eddies. You can use the hybrid model with RANS, a turbulent model of small calculation load.

## Radiation

Heat transfer by infrared-ray radiation can be considered by setting emissivity and temperature difference between objects. You can choose VF (view factor) method and FLUX method as a calculation method. You can also consider wavelength dependence of radiation, transmission, absorption, refraction, diffusion, and reflection. In FLUX method, you can also consider directionality.

## Zooming

When a target phenomenon is in a small range affected by a wide range of its surrounding area, analysis results of the surrounding area can be used for an analysis of the target phenomenon as boundary conditions to reduce the calculation load. The function can be used, for example, in an aerodynamic analysis of an automobile.

## Fan model

You can set conditions considering P-Q characteristics of fans without creating the shape of fans. In addition, as for swirling components which are not obtained from P-Q characteristics of axial flow fans, “non-dimensional swirl coefficient model” suggested by The Japan Society of Mechanical Engineers, Research sub-committee has been adopted. By using the model, simulations closer to real phenomena can be done.

## Joule heating

Joule heat, which is generated when an electric current travels through an object with an electric resistance, can be considered. By setting a wiring of a conductor and specifying values of electric current and voltage, the wiring works as a heat source automatically.

## HeatPathView

The information on temperature of each part and a comprehensive amount of heat release obtained in post-processing of a general CFD analysis is not enough to know the heat path. HeatPathView displays heat paths and the amount of heat transfer in the whole computational domain in a diagram, a graph, and a table, allowing you to find the bottleneck of the heat paths easily.

## FluidBearingDesigner

The function creates groove patterns of fluid bearings (dynamic-pressure bearing) and generates mesh. You can select the shape of grooves such as journal and thrust and materials such as porous material. From calculation results, you can obtain parameters for designing fluid bearings such as axial force and drag coefficient.