Convergent Science Inc. CFD Software and Consulting Services

Experts in Engine CFD Analysis

The CONV ERGET M CFD code

automatically generates a high quality

orthogonal mesh at run-time thus

eliminating all user meshing time

CONVERGETM automatically adds mesh

resolution w hen and w here it is needed

based upon field variables to maximize

accuracy w hile minimizing the run-time

CONVERGETM is loaded w ith the

physical models for spray, turbulence

and combustion needed to accurately

simulate all engine types including

Diesel, gasoline, hydrogen, natural gas,

dual fuel and HCCI

CONVERGETM runs great in parallel

Use CONVERGETM CFD Software for In-Cylinder Spray and Combustion Analysis and Never Make a Mesh Again

contact@convergecfd.com www.convergecfd.com (830) 481-6434

Optimization with CONVERGETM : Let the computer find the best design

Velocity (left) and temperature contours (right) for SI engine analysis

using detailed chemistry and adaptive mesh refinement (AMR)

CONV ERGETM comes equipped w ith a pow erful optimization

algorithm called CONGO. With CONGO, a merit function (often

a combination of emissions and fuel consumption) is used to

rate the f itness of each design. A population of designs is

automatically run in parallel across many computers, stopping

w hen the time allotted has been reached.

Common optimization parameters include

• Settings (such as spray details, EGR level and spark timing)

• Tables (such as valve lift profiles and spray rate shape)

• Parameterized Geometry (such as piston shape)

Use CONGO and let CONV ERGETM automatically f ind the

optimum design.

Conjugate Heat Transfer (CHT)

modeling with CONVERGETM v2.1

In CONV ERGETM v2.1, the user can readily solve for

the f low and heat transfer in all f luid and solid

components (“conjugate heat transfer”).

As is alw ays the case w ith CONV ERGETM, a body

f itted mesh for all the f luid and solid entit ies is

generated automatically at run-time, thus eliminating

all user meshing time and streamlining the analysis.

Appropriate super-cycling techniques for handling

the disparate time-scales associated w ith heat

transfer and fluid f low are available to minimize the

run-times associated w ith conjugate heat transfer.

Optimum piston bowl shape (top) and merit

map for CONGO genetic algorithm analysis

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NOx+HC (g/kg-fuel)

Optimum

Conjugate heat transfer (both fluid and solid) simulated

in CONVERGE without any coupling with other tools

Increase Productivity

No user meshing time

Parallel speedup

Handle all geometry types

Handle moving parts

automatically

Increase Accuracy

Orthogonal mesh

Adaptive mesh refinement

Grid scaling & embedding

Perform grid resolution

studies without making any

meshes

Key Physical Models

• SAGE detailed chemistry

solver

• Advanced turbulence

(including LES)

• Spray break-up

• Droplet coll ision and

coalescence

• Multi-component vaporization

• Combustion suite

• Wall fi lm

• Genetic algorithm for

optimization studies

• User routines for custom

model implementation

Multi-component Vaporization

When using detailed chemistry

w ith CONV ERGETM, the user

can specify any desired

chemical mechanism – there is

not a limit on the number of

species or reactions. To

minimize run t ime, it is

obviously desirable to use the

smallest mechanism possible

which w ill provide accurate

results.

To this end, CSI has

implemented a parallel version

of the latest state of the art

mechanism reduction tool,

“Parallel Directed Relation

Graph w ith Error Propagation

and Sens itivity“ (PDRGEPSA).

Unimportant species and

reactions are removed from the

mechanism w ith the goal of

minimiz ing the mechanism size

w hile maximizing the accuracy.

The multi-component vaporization capabilities

of CONVERGET M can handle all modern fuel

injection strategies including dual fuel, ethanol,

cold start and w ater injection.

Each liquid can be comprised of any number of

components. The vaporization algorithm

sources each of the species individually based

upon the component distillation properties.

Regardless of the fuel injection strategy, SAGE-

Multizone can be used to determine the

reaction rates for any mixture of gases.

SAGE-Multizone with n-Dimensional bins for speeding up multi-fuel CFD simulations For some cases such as multi-fuel applications, two

dimensional zoning (i.e. temperature and phi) is insuff icient

to accurately model the combustion. For these cases,

CONVERGE allow s an arbitrary number of bins to be used.

Schematic of PDRGEPSA Mechanism Reduction Algorithm

SAGE-Multizone dramatically reduces the run time associated with detailed chemistry

Including detailed chemistry is essential for accurately

modeling kinetically limited phenomena such as f lame

propagation, auto-ignition and emissions. For this reason,

CONVERGETM comes standard w ith the SAGE detailed

chemistry solver for combustion modeling.

Convergent Science Inc. has licensed the Multi-Zone

Chemistry Solver from Lawrence Livermore National

Laboratory and implemented this into CONVERGETM to

enhance the capabilities of SAGE.

SAGE-Multizone drastically reduces the run-time associated

with detailed chemistry simulations. Typical chemistry

speedups over standard SAGE are 15X for Diesel engines and

50X for spark ignited engines. SAGE-Multizone is available in

the current release of CONVERGETM.

Auto-ignition locations (red) and liquid spray droplets for dual fuel

(Iso-octane+Diesel) test case.

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Typical run time for a premixed engine simulation

showing the dramatic reduction in run time

associated with SAGE-Multizone

CONVERGETM Chemical

Mechanism Reduction

Iso-surface of temperature showing the flame front

(red) and locations of auto-ignition (blue) for spark ignited engine.