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In physics and engineering, fluids are substances that can flow and take the shape of their container, including both liquids and gases. Fluids are characterized by their ability to deform continuously under applied shear stress, which distinguishes them from solids. Their behavior is governed by principles such as conservation of mass, momentum, and energy, and they can exhibit complex phenomena like turbulence, heat transfer, and chemical reactions.
In Ansys simulation software, particularly Ansys Fluent, fluids are modeled using computational fluid dynamics (CFD) techniques. Fluent provides advanced physics models to simulate a wide range of fluid phenomena, including incompressible and compressible flows, laminar and turbulent regimes, single and multiphase flows, heat and mass transfer, and chemical reactions. Users can create and mesh complex geometries, assign material properties, configure physics models, and apply boundary conditions to accurately represent real-world fluid systems. The software supports steady-state and transient analyses, and includes features for modeling porous media, moving reference frames, and conjugate heat transfer, among others. This enables engineers to analyze and optimize designs such as pumps, fans, heat exchangers, and aerodynamic surfaces.
Would you like guidance on setting up a basic fluid flow simulation in Ansys Fluent?
References:
January 20, 2026 at 9:11 am
Asavari Bhusari
Administrator
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January 20, 2026 at 9:12 am
directcustomer
Subscriber
test comment from My forum YH
January 20, 2026 at 9:12 am
AnsysGPT
Question to Ansys Assistant
what is bolt pretension in mechanical?
Response from Ansys Assistant
Bolt pretension in mechanical engineering refers to the initial load or tension that is intentionally applied to a bolt during assembly, before any external loads are introduced. This pretension ensures that the bolt and the connected components remain securely fastened under operating conditions, preventing separation or loosening due to vibrations, thermal effects, or applied loads. In simulation, bolt pretension is modeled as a specific boundary condition that represents this pre-load, which is critical for accurately assessing the structural integrity and behavior of bolted joints.
In Ansys Mechanical, bolt pretension can be applied to various geometric entities such as cylindrical faces, straight edges, or beam connections. The pretension load is defined by specifying either a force or a displacement, and it is typically used in static structural analyses to simulate the effect of tightening the bolt. This pre-load helps maintain the connection between mating parts and distributes working loads across the assembly. It is important to note that bolt pretension should generally be applied to non-bonded contact surfaces, as bonded contacts restrict the necessary motion for pretensioning.
Would you like guidance on how to set up bolt pretension in an Ansys Mechanical simulation?
References:
January 20, 2026 at 9:14 am
directcustomer
Subscriber
what is turbulence model?
January 20, 2026 at 9:14 am
AnsysGPT
Question to Ansys Assistant
what is turbulence model?
Response from Ansys Assistant
A turbulence model in engineering simulation is a mathematical approach used to predict the effects of turbulence in fluid flow without resolving all the smallest turbulent fluctuations directly. Turbulence is inherently complex and occurs in most industrial fluid applications, making direct simulation computationally expensive or impractical. Instead, turbulence models use approximations—often based on the Reynolds Averaged Navier-Stokes (RANS) equations—to represent the averaged effect of turbulent eddies on the flow. These models can be classified as eddy-viscosity models or Reynolds stress models, each suited to different types of flow scenarios. By applying a turbulence model, engineers can simulate aerodynamics, heat transfer, and mixing performance with reasonable accuracy and computational efficiency.
In Ansys software, turbulence models are selected and configured as part of the physics setup for a fluid simulation. For example, in Ansys Discovery, the k-omega SST turbulence model is commonly used as a default for both steady-state and transient simulations, but other models are available depending on the specific requirements of the application. The choice of turbulence model can significantly impact the accuracy and reliability of simulation results, especially in cases involving fluid-structure interactions or complex flow geometries. The software allows users to go deeper into the analysis, capturing the dynamic interactions between turbulent flows and structures to ensure that designs meet performance and durability requirements.
Would you like to know more about how to select the most appropriate turbulence model for your specific simulation scenario?
References:
January 22, 2026 at 6:39 pm
directcustomer
Subscriber
what is fluids?
January 22, 2026 at 6:39 pm
AnsysGPT
Question to Ansys Assistant
what is fluids?
Response from Ansys Assistant
Definition of Fluids in Physics
In physics, a fluid is defined as any substance that deforms continuously when subjected to a tangential or shear stress, no matter how small that stress may be. This means that fluids will flow or change shape when a force is applied, unlike solids which resist deformation. Both liquids and gases are considered fluids because they share this property of continuous deformation under shear stress.
Fluids are distinguished from solids by their ability to take the shape of their container and to flow. The study of fluids includes examining their physical properties, such as viscosity (resistance to flow), and classifying different types of fluid flows. In fluid mechanics, fluids are often treated as a continuum, meaning their properties are assumed to be distributed smoothly throughout the region of interest.
Would you like more information on how fluids are classified or examples of fluid behavior in engineering applications?
January 22, 2026 at 6:41 pm
directcustomer
Subscriber
what is fluids?
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January 22, 2026 at 6:41 pm
AnsysGPT
Question to Ansys Assistant
what is fluids?
Response from Ansys Assistant
Definition of Fluids in Physics
In physics, a fluid is defined as a substance that deforms continuously when subjected to a tangential or shear stress, no matter how small that stress may be. This means that fluids will flow or change shape as long as a force is applied, unlike solids which resist deformation. Both liquids and gases are considered fluids because they share this property of continuous deformation under shear stress.
Fluids are characterized by their ability to take the shape of their container and by properties such as density, viscosity, and pressure. In fluid mechanics, fluids are often treated as a continuum, meaning their properties are assumed to be distributed smoothly and continuously throughout the region of interest. This allows for the analysis of fluid flow, pressure variations, and other behaviors using mathematical models.
Common examples of fluids include water, air, oil, and mercury. The study of fluids and their behavior is fundamental to many engineering and scientific applications, such as aerodynamics, hydraulics, and weather prediction.
Would you like more details on how fluids are modeled in computational simulations?
February 4, 2026 at 7:19 am
directcustomer
Subscriber
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February 4, 2026 at 7:19 am
AnsysGPT
Question to Ansys Assistant
what is the non newtonian fluid?
Response from Ansys Assistant
Definition of Non-Newtonian Fluid
A non-Newtonian fluid is a type of fluid whose shear stress is not linearly related to the shear strain rate. Unlike Newtonian fluids, which obey Newton's law of viscosity (where shear stress is directly proportional to the velocity gradient), non-Newtonian fluids exhibit a more complex relationship between shear stress and strain rate. This means that their viscosity can change depending on the applied force or shear rate. Examples of non-Newtonian fluids include blood, polymer solutions, colloidal suspensions, and certain pastes or gels.
Behavioral Differences from Newtonian Fluids
Newtonian fluids, such as water and air, have a constant viscosity regardless of the shear rate applied to them. In contrast, non-Newtonian fluids can exhibit behaviors such as shear thinning (viscosity decreases with increasing shear rate), shear thickening (viscosity increases with increasing shear rate), viscoelasticity (exhibiting both viscous and elastic properties), or yield stress (requiring a minimum stress to start flowing). The specific behavior depends on the fluid's composition and structure. Rheological models, such as the Bingham plastic, power law, Herschel-Bulkley, and Casson models, are often used to describe and predict the flow characteristics of non-Newtonian fluids.
Examples and Applications
Blood is a classic example of a non-Newtonian fluid, showing shear thinning and viscoelastic behavior due to its complex composition of cells and proteins. Other examples include polymer melts, toothpaste, ketchup, and certain industrial suspensions. Understanding non-Newtonian behavior is crucial in fields like biomedical engineering, chemical processing, and materials science, where accurate modeling of fluid flow is required for design and analysis.
Would you like more details on how Ansys software handles non-Newtonian fluid modeling?
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The Ansys Learning Forum is a public forum. You are prohibited from providing (i) information that is confidential to You, your employer, or any third party, (ii) Personal Data or individually identifiable health information, (iii) any information that is U.S. Government Classified, Controlled Unclassified Information, International Traffic in Arms Regulators (ITAR) or Export Administration Regulators (EAR) controlled or otherwise have been determined by the United States Government or by a foreign government to require protection against unauthorized disclosure for reasons of national security, or (iv) topics or information restricted by the People's Republic of China data protection and privacy laws.
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