CFD Direct is pleased to announce the release of version 9 of CFD Direct From the Cloud™ (CFDDFC®). CFDDFC v9 is available as a pay-as-you-go image for Amazon Elastic Cloud Compute (EC2) on Amazon Web Services (AWS) Marketplace. It is available as:

  • ­“Standard” CFDDFC, for instances running processors with x86 architecture from Intel and AMD ;
  • CFDDFC (Arm), for instances with AWS Graviton processors with Arm architecture.

“Standard” CFDDFC

CFDDFC is the marketplace product for the majority of instance types, based on x86 processors such as those from Intel and AMD. It provides a full desktop environment with graphical applications, accessible using the X2Go remote desktop (see below), including:

CFD Direct from the Cloud 9 Remote Desktop


CFDDFC (Arm) is the marketplace product for instances using processors with Arm architecture, notably AWS’s C6g instances with their Graviton processor. CFDDFC (Arm) is a server-only distribution without remote desktop and graphical applications. CFDDFC (Arm) includes:

Single Instances

EC2 includes Compute Optimized instances for compute-intensive workloads. The C5 instances have a range of sizes up to c5.24xlarge which contains 48 physical cores. C5n instances are a variant of C5 that provide significantly higher network performance across all instance sizes, with the  largest C5n instance, c5n.18xlarge, containing 36 physical cores.

The C6g instances with the Graviton2 processors include a range of instances sizes up to c6g.16xlarge which includes 64 physical cores. The clock speed is lower than the C5 instances, making the performance of c6g.16xlarge and c5n.18xlarge broadly similar. C6gn instances are the variant of C6g with significantly higher network performance.

The C6g instances provide up to 40% savings in on-demand running costs for equivalent performance. This makes C6g very attractive for: batch runs, where graphics is not needed; on-demand runs, which cannot exploit the cost savings of spot instances.

Clusters of Instances

CFDDFC v9 provides high performance computing (HPC) by clustering instances with faster networking to deliver good scalability. CFDDFC supports Elastic Network Adapter (ENA) which provides the high throughput, low latency networking required by clusters. Both C5n and C6gn instances support ENA, with c5n.18xlarge and c6gn.16xlarge having 100 Gbps of network bandwidth compared to 25 Gbps with c5.18xlarge and c6g.16xlarge

A cluster of C5n instances delivers 70%-90% scaling at 504 cores.  This performance is significantly better than standard C5 instances, which exhibit scaling below 50% at the same number of cores.  Even with the higher price of ~25%,  C5n instances are more cost-effective than C5 when clustering multiple instances. 

CFDDFC supports Elastic Fabric Adapter (EFA), an additional network interface for HPC applications running on c5n.18xlarge and c6gn.16xlarge instances. CFD Direct previewed the EFA technology, which showed ~70% scaling at 1008 cores for meshes of 100 k cells per core and linear scaling at 1008 cores for a fixed mesh size of 97 m cells.

Command Line Interface

The cfddfc command line interface (CLI) manages instances of CFDDFC on AWS, transfers data to and from instances and provides convenient access to the instance by remote desktop or SSH login. It automatically selects the relevant CFDDFC v9 product to suit the instance type selected at launch. For example, the CFDDFC (Arm) product is used with the following launch command for a 64 core c6g.16xlargeinstance:

cfddfc launch -instance c6g.16xlarge

A user could then create a cluster of 4 instances, i.e. 256 cores, by adding 3 slave instances using the cluster subcommand, e.g.

cfddfc cluster -slaves 3

Once the slave instances are running, the cluster is fully operational.

CFDDFC® v9 Released